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# Can the speed of an object change if the net work done on it is zero

### If the net work is zero

• The net work done by all forces acting on an object is equal to the kinetic energy change of that object. If the net work is zero, that means there is no kinetic energy change. That means that once the object being lifted is in motion, it moves up at constant speed
• An object's velocity will change if a net force acts on the object. If two object have the same acceleration, they are under the influence of equal forces. The net force which acts on an object which remains at rest is zero. A truck initially moving at a constant velocity will slow down unless a small net force is applie
• Solution: The work done is equal to the change in kinetic energy. So if the net work done on an object is zero, its change in kinetic energy is also zero. Thus, the speed of the object will remain the same
• This problem has been solved! See the answer. Part C) During a certain time interval, the net work done on an object is zero joules. We can be certain that ____. the object was at rest at the end of this interval. the object's final speed was the same as its initial speed. the object was at rest during this entire interval

### true or false If a net force acts on an object, the object

If the net work done on an object is negative, then the object's kinetic energy A) decreases. B) is zero. C) remains the same. D) increases. 2) A An object is released from rest a height h above the ground. A second object with four times the mass of the first if released from the same height Zero Work: If the direction of the force and the displacement are perpendicular to each other, the total work done by the force on the object is null. For example, when we thrust hard against a wall, the force we are applying on the wall does not work, because in this case, the displacement of the wall is d = 0 If a force transfers energy to an object, is the work done by the force on the object positive or negative? Positive. Speed is zero. can the external force change the net momentum of the system? No Another situation in which work is zero despite a nonzero force is when the displacement of the object is zero. This is seen in the equation of work: W = F * d = F * 0 = 0. Pushing against a wall. Sure. If the force acts consistently perpendicular to the direction of travel, the direction will change, but the speed, which is simply the magnitude of the velocity ($\lvert v\rvert$), will not change. An example of this the Earth rev..

There is a strong connection between work and energy, in a sense that when there is a net force doing work on an object, the object's kinetic energy will change by an amount equal to the work done: Note that the work in this equation is the work done by the net force, rather than the work done by an individual force Is the work done on the object by F 1 positive, negative, or zero? Is the work done on the object by F 2 positive, negative, or zero? Is the net work done on the object positive, negative, or zero? (b) An object travels from point A to point B while two constant forces of unequal magnitude are exerted on it, as shown in the figure on the right If positive work is done, then the object will gain energy. If negative work is done, then the object will lose energy. When a net force does work on an object, then there is always a change in the kinetic energy of the object. This is because the object experiences an acceleration and therefore a change in velocity

the object is equal to the net work done on it: ∆K = Kf −Ki = Wnet (6.13) 6.1.5 Power In certain applications we are interested in the rate at which work is done by a force. If an amount of work W is done in a time ∆t, then we say that the average power P due to the force is P = W ∆t (6.14 Zero net force does not necessarily imply zero velocity(a skydiver's terminal speed will be greater than 100 mph) Zero force constant velocity, v = 0 is a special case of constant velocity. A parachutes reduce the terminal speed to about 10 mph. Newton's 2ndLaw To change the velocity of an object a net force must be applied to it When the net force acting on an object is not zero, then the net work done on the object is W net = F net ·d. When a net force acts on an object, then the object accelerates, it changes its velocity. Can we express the work done by the net force in terms of this change in velocity? Assume an object is moving along a straight line and a. Follow Us: If the net force acting on an object is zero, then it means that the object's velocity is constant and the object isn't speeding up or slowing down. That is, there is no acceleration on an object with zero net force. Force is not required for an object to continue moving or staying at a state of rest This will be equivalent to Approach 1. If the resultant force parallel to the direction of motion is zero, no net work will be done. Remember that work done tells you about the energy transfer to or from an object by means of a force. That is why we can have zero net work done even if multiple large forces are acting on an object

If an object moves with constant velocity, what is the net work being done on it? Zero because the net force acting on it is zero and thus the work must also be zero A force that exerts positive work does what to speed true or false If a net force acts on an object, the object's speed will change. An object's velocity will change if a net force acts on the object. If two object have the same acceleration, they are under the influence of equa The net work W net is the work done by the net force acting on an object. Work done on an object transfers energy to the object. The translational kinetic energy of an object of mass m moving at speed v is $\text{KE}=\frac{1}{2}mv^{2}\$/extract_itex] W g≡ F g•d ∫ x = F g• d =mgΔy where F g=(mg)( −ˆ j ) and g=9.81m/s2 If an object is displaced upward (Δ y positive), then the work done by the gravitational force on the object is negative. If an object is displaced downward (Δy negative), then the work done by the gravitational force on the object is positive. 2 € W sprin The angular speed of the system remains the same because the net torque on the merry-go-round is zero N ⋅ m. 16. Which one of the following statements concerning kinetic energy is true? Kinetic energy can be measured in watts. Kinetic energy is always equal to the potential energy ### Mastering Physics Solutions Chapter 7 Work And Kinetic • This requires a greater amount of internal contraction and release of our muscle fibers, and hence internal work in our bodies. But the work done on the box is zero since by moving in a straight line at constant speed, its energy is remaining the same • ed without knowing the mass of the object • With zero net force, there is zero change in momentum and the cart moves along at a constant speed • The Work/Energy Equation says that the work done on an object (by the net force on it) equals its change in kinetic energy. So, to figure out how much work is done on an object, just calculate the change in its kinetic energy... If the Force Acts in the Direction That the Object Moves: This force will tend to increase the object's speed Rotation around a fixed axis is a special case of rotational motion. The fixed-axis hypothesis excludes the possibility of an axis changing its orientation and cannot describe such phenomena as wobbling or precession.According to Euler's rotation theorem, simultaneous rotation along a number of stationary axes at the same time is impossible; if two rotations are forced at the same time, a new. Add up the total amount of work done by each force. Set this total work equal to the change in kinetic energy and solve for any unknown parameter. Check your answers. If the object is traveling at a constant speed or zero acceleration, the total work done should be zero and match the change in kinetic energy The total work done on an object determines its motion. If the total work is zero, the object moves at constant speed or is at rest. The object accelerates if the total work has a value other than zero. C- Kinetic Energy and Work The work can be defined as the change in the kinetic energy. If a body changes its velocity from v 1 to v • Forces can change the physical state of an object • Even though the work is zero in (a), gaining speed. Is the work done by the gravitational force exerted on the ball during this motion positive or negative? • Ball's energy now increases, so work is positive (force & -To calculate the work done on an object by a force during a displacement, we use only the force component along the object's displacement. The force component perpendicular to the displacement does zero work. W F x d Fcos d F d (7.3) - Assumptions: 1) F=cte, 2) Object particle-like. 90 0 180 90 9 ### Solved: Part C) During A Certain Time Interval, The Net Wo 1. Work done on an object by a constant force is given by W = Fdcos φ or W = F • d a. φ is the angle between the force and the direction of displacement 7.5 Work and Kinetic Energy 1. The change in kinetic energy is equal to the net work done on a particle Δ K = K f - K i = W 7.6 Work done by Gravitational Force 1. W g = mgdcos φ a 2. • The change in kinetic energy of a particle is equal to the net work done on the particle. • Net work is the work done by the net force acting on a particle. • The work done is equal to the total energy transferred to the particle by means of mechanical forces. 7.5: Work and Kinetic Energy Note: The theorem holds true for both positive. 3. When B is non-uniform, then there is net force. Can be shown that the direction of this force is such that magnetic dipole moment is attracted to the region of high B. ÎMagnetic force does no work. But when two bar magnets are attracted to each other, there must be work done by B. Something is not right here 4. Work is zero if applied force is zero (W=0 if F=0): If a block is moving on a smooth horizontal surface (frictionless), no work will be done. Note that the block may have large displacement but no work gets done. Work is zero if Cos θ is zero or θ = Π/2. this explains why no work is done by the porter in carrying the load 5. Work is done whenever energy is transferred from one store to another. Mechanical work involves using a force to move an object. Electrical work involves a current transferring energy. Work done (J) = Force (N) x Distance (m) Example: During braking, a force of 2000N is applied to the brakes of a car. The car takes 20m to come to a stop 6. Heavier objects (greater mass) resist change more than lighter objects. Example: Pushing a bicycle or a Cadillac, or stopping them once moving. The more massive the object (more inertia) the harder it is to start or stop. The Cadillac has more of a tendency to stay stationary (or continue moving), and resist a change in motion than a bicycle 7. An object experience a net zero external unbalanced force. Is it possible for the object to be travelling with a non-zero velocity? If yes, state the conditions that must be placed on the magnitude and direction of the velocity. If no, provide a reason. The driver of a car moving at a speed of 10 m s. down with constant speed. • Zero net force does not necessarily imply zero velocity (a skydiver's terminal speed will be greater than 100 mph) • Zero force constant velocity, v = 0 is a special case of constant velocity. A parachutes reduce the terminal speed to about 10 mph Acceleration can be non-zero only if there is a net external force on the body. Speed up or slow down a moving object 4) Change the direction of the motion Further by work-energy theorem as Work done = change in kinetic energy ∆K = 0 (because ∆W = 0) i.e. K (KE) remains constant Access the answers of NCERT Solutions for Class 11 Physics Chapter 6 Work, Energy and Power. Que.1.The sign of work done by a force on a body is important to understand. State carefully if the following quantities are positive or negative: (a) work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket ### Work Done - Definition, Formula, Examples and Important FAQ An object moves in a circle at constant speed. The work done by the centripetal force is zero because: a. The displacement for each revolution is zero. b. The average force for each revolution is zero. c. There is no friction. d. The centripetal force is perpendicular to the velocity. e. The magnitude of the acceleration is zero . Ans. D . 7 The work done by the applied force is 12 N x 0.1 m = 1.2 J. The net work done is (12 N - 10 N) x 0.1 m = 0.2 J. This net work is the change in KE of the book. (so ). The work done over the 0.8 m from 0.1 m to 0.9 m is 10 N x 0.8 m = 8 J, but the net force is ZERO so the net work is ZERO The net work done on a particle is equal to the change in its Kinetic Energy. So if the net work is zero the Kinetic Energy remains constant and that means the speed , too, remains constant. Q7.9 When a punter kicks a football, is he doing any work on the ball while his toe is in contact with it ### physics midterm 2 Flashcards Quizle Alternating Current Work. Leave a reply. Work and Kinetic Energy. * When a net force does work on a rigid body, it causes the body's speed to change. * The work done by the net force is the same as the sum-total of the work done by the action of every force acting the body. If you add up the work done by each of the forces acting on a body.  The net work Wnet is the work done by the net force acting on an object. Work done on an object transfers energy to the object. The translational kinetic energy of an object of mass m moving at speed v is KE = 1 2mv2. The work-energy theorem states that the net work Wnet on a system changes its kinetic energy, Wnet = 1 2mv2 − 1 2mv2 0 As we discussed in the previous section, forces cause objects to move. When a net force acting on a physical system has a component in the direction of its motion, there is work done. Recalling the Energy-Interaction Model, when work is being done Equation 1.2.1 becomes: \[\Delta E_{tot}=W.\ Force: Force is defined as a push or a pull that can cause any object with a mass to change its velocity and acceleration. Force is a vector quantity and has both a magnitude and a direction. If the force acting on an object is zero irrespective of the state of the object (dynamic or static) that work done by the force is zero ### If there is a net nonzero force on a moving object, is it • The net work done by a conservation force as the object moves from point #1 to point #2 and back to point #1 is zero. #2 #1 W W 12 21 W 12 = −W 21 • The work done by a conservative force in moving the object from point #1 to point #2 does not depend on the path between the two points The work done against a force is the negative of the work done by the force. The work done by a normal or frictional contact force must be determined in each particular case. The work done by the force of gravity, on an object near the surface of Earth, depends only on the weight of the object and the difference in height through which it moved ### Video: Is it possible that a net external force on a system is Strategy: Apply equation 7-3, which says that the work done on an object is positive if the force and the displacement are along the same direction, but zero if the force is perpendicular to the displacement. Solution: 1. (a) As the pendulum bob swings from point II to point III, th The work done by the force F on the object as it undergoes a displacement d is defined as. The work done by the force F is zero if: * d = 0: displacement equal to zero * [phi] = 90deg.: force perpendicular to displacement. Figure 7.2. Positive or Negative Work. The work done by the force F can be positive or negative, depending on [phi] Neglecting any change in kinetic energy of the block (either because the speed was constant or was essentially zero during the lifting process), the work done by either Mark and David equals the increase in the gravitational potential energy of the block as it is lifted from the ground to the truck bed (a) The net work done by all the forces acting on the pack is zero joules. (b) The work done on the pack by the normal force of the mountain is zero joules. (c) The work done on the pack by gravity is zero joules. (d) The gravitational potential energy of the pack is increasing. (e) The climber does positive work in pulling the pack up the. If the conservative force does positive work then the change in potential energy is negative. Therefore: \[W_{\text{conservative}}=-\Delta E_p$ Non-conservative force A non-conservative force is one for which work done on the object depends on the path taken by the object

via the work done by friction. The work done by the friction force F sover a displacement xis just F sxsince F sis constant. If the car of mass mhas initial velocity v, then 1 2 mv2 = F sx (8) x= mv2 2F s (9) Since the stopping distance x/v2, if the speed is doubled the car skids four times farther. 8 work done = force × distance. work done = 600 N × 40 m. work done = 24,000 J (or 24 kJ) Question. In a scrum, a rugby team pushes the other team backwards 5 m using a force of 1,000 N. Calculate. 2. If the work done from a to b along path 1 as W ab,1 and the work done from b back to a along path 2 as W ba,2. If the force is conservative, then the net work done during the round trip must be zero If the force is conservative, D. Sample Problem 1. Figure below shows my poor meatball, all covered with cheese, rollin See Page 1. . Generalize from your results to part 2 to describe how the speed of an object changes (speeds up, slows down, or remains the same) if the net work is a) positive, b) negative, c) zero. 5. Consider a new set-up: glider A is pulled by a string across a level, frictionless table. The string exerts a constant horizontal force

If the net work done is negative, then the particle's kinetic energy decreases by the amount of the work.  From Newton's second law , it can be shown that work on a free (no fields), rigid (no internal degrees of freedom) body, is equal to the change in kinetic energy E k corresponding to the linear velocity and angular velocity of that body And finally the network done on particle as it moves from 0.0.8 would be first. We'll start by calculating the kinetic energy a queen a The equation for kinetic energy, simply 1/2 times the mass times velocity squared. Remember that the velocity here is not a vector. It's really the magnitude the lost the vector otherwise known as the Speed Square

Solution Set - Work and Energy - Physics 104. Answers - Work and Energy. 1. Work equals the force F times the displacement s times the cosine of the angle F, s between the force F and the displacement s: W = (Fs cos F, s) If we rewrite work as W = (F cos F, s )s, we see from Fig. 1b that we may say, alternatively, that work is the component of. 19. Newton's first law of motion states than an object's motion will not change unless O the net force acting on it is greater than zero. O a force continues to be applied to the object. O its inertia is stronger than the applied force. O the object has no inertia. 20. Overcoming an object's inertia always requires a(n) O large mass (b) The net work done by all the forces acting on the crate is zero joules. (c) The work done on the crate by the normal force of the plane is zero joules. (d) The donkey does positive work in pulling the crate up the incline. (e) The work done on the object by gravity is zero joules. 30 A horizontal force Fa of magnitude 20.0 N is applied to a 3.00 kg psychology book as the book slides a distance d =0.500 m up a frictionless ramp at angle θ = 30.0°

### Work and energy - Boston Universit

If the resultant force is zero, the effect depends on the initial state of the object. If it is already moving, it will continue to move at the same velocity, in other words, at the same speed and in the same direction as when the resultant forces became zero. If it was stationary to begin with, then it will remain stationary 24.During which interval is the object's acceleration the greatest? A) zero B) increasing C)decreasing D) constant, but not zero 25.During the interval t = 8 seconds to t = 10 seconds, the speed of the object is A) 10 m/sec B)25 m/sec C) 150 m/sec D) 250 m/sec 26.What is the maximum speed reached by the object during the 10 seconds of travel the object being moved at a constant rate of distance over time. The object had a positive or negative velocity (speed) during that duration of time, depending on the direction be traveled (toward/away). These can be seen as incline and decline in the data collected above (see descriptions for B and D in Part A) (a) Calculate the work done on the object by the force during time interval At = 5.0 s. (8 pts) (b) What is the speed of the particle at the position F2 ? (4 pts) x 32-—1 C 32 (c) What is the average power supplied by the force during time interval At = 5.0 s. (3 pts

C) The angular speed of the system increases because the moment of inertia of the system has decreased. D) The angular speed of the system decreases because the moment of inertia of the system has decreased. E) The angular speed of the system remains the same because the net torque on the merry-go-round is zero N ⋅ m. 0!p=F!t=(mg)!t!= s r. Total work done on an object is related to the change in kinetic energy of the object, just as total force on an object is related to the acceleration. W net = ΔKE This relation will be restated as Conservation of Energy and used in a wide variety of problems. However, in this form, it is handy for finding the work done by an unknown force

### Physics Laboratory

work can be done by the electric field to move an object along the surface, and thus we must have Es⋅=d 0 Therefore, equipotential surfaces are always perpendicular to the direction of the electric field (the field lines). The potential lines indicate surfaces at the same electric potential, and the spacing is In this problem, you will learn about the relationship between the work done on an object and the kinetic energy of that object. The kinetic energy of an object of mass moving at a speed is defined as . It seems reasonable to say that the speed of an object--and, therefore, its kinetic energy--can be changed by performing work on the object the work done in the opposite direction is slowing the object down. For an incorrect statement, the opposite is true: the net work done to the particle must be zero or negative. A) Positive work is done so this is incorrect. B) Positive work is done so this is incorrect. C) Positive work is done so this is incorrect on an inclined plane is zero, the block (1) must be at rest (2) must be accelerating (3) may be slowing down (4) may be moving at constant speed 4 The greatest increase in the inertia of an object would be produced by increasing the (1) mass of the object from 1.0 kg to 2.0 kg (2) net force applied to the object from 1.0 N to 2.0 Q14.10 Explain why no work is done on a planet as it moves in a circular orbit around the Sun, even though a gravitational force is acting on the planet. What is the net work done ona planet during each revolution as it moves around the Sun in an elliptical orbit?. In a circular orbit, the gravitational force is always perpendicular to the motion so the work done is always zero

The effect of the angle between force and displacement on work. When the angle between the force and displacement = zero , The work done is maximum when the direction of force is the same as the direction of displacement , such as a person pulling an object through a certain distance . W = F d cos 0° = F d. When θ =90° , The work done is. Since the normal force and the direction of motion both point up, we get a positive work done by the normal force. However, since the force of gravity is doing a larger negative work, the net work is negative and net work is what equals a change in kinetic energy. Reply Delet work done by the weightlifter who is 1.5 meters tall, the work done by the weightlifter who is 2.0 meters tall is (1) less (2) greater (3) the same 13 A 45.0-kilogram boy is riding a 15.0-kilogram bicycle with a speed of 8.00 meters per second. What is the combined kinetic energy of the boy and the bicycle? (1) 240. J (3) 1440 J (2) 480. J (4. 120 seconds. Q. After a cannonball is fired into frictionless space, the amount of force needed to keep it going equals. answer choices. twice the force with which it was fired. the same amount of force with which it was fired. 1/2 the force with which it was fired. zero, since no force is requires to keep it moving 15. An elevator is lifted vertically upwards at a constant speed. Is the net work done on the elevator negative, positive, or zero? Explain. 16. Can the net work done on an object during a displacement be negative? Explain

Change in the kinetic net work done on energy of a particle the particle The work-kinetic energy theorem holds for both positive and negative values of If 0 0 If 0 0 net net f i f i net f i f i W WKKKK WKKKK The work-energy theorem: when a net external force does work W on an object, the kinetic energy of th The work done would then be: This work would be equal to the change in kinetic energy. Since the piano starts from rest, the initial kinetic energy is zero. Now I can put this together and solve. the work done by the force on an object moving from one point to another depends i.e., the change in potential energy is equal to the negative work done by the conservative force. The net force is zero. (C) No nonconservative work. (D) The mechanical energy is never conserved.. Net work is defined to be the sum of work done on an object. The net work can be written in terms of the net force on an object. and use the equation studied in Motion Equations for Constant Acceleration in One Dimension for the change in speed over a distance d d To reduce the kinetic energy of the package to zero, the work W fr W fr. The work done on the object by the net force = the object's change in kinetic energy. Very Important Fine Print! It needs to be emphasized that the work/energy equation only applies to work done by the net force in a mechanical system - the work done by just any old force may or may not show up as kinetic energy, but the work done by the net.

Which of the following is always true for an object moving in a straight line at constant speed? A. No forces act on the object. B. No resultant force acts on the object. C. The momentum of the object is zero. D. No work is being done on the object So if an object is moving in a horizontal circle at constant speed, the centripetal force does not do work and cannot alter the total mechanical energy of the object. For this reason, the kinetic energy and therefore, the speed of the object will remain constant. The force can indeed accelerate the object - by changing its direction - but it.

If the net work done on a particle is zero, which of the following statements must be true? (a) The velocity is zero. (b) The velocity is decreased. (c) The velocity is unchanged. (d) The speed is unchanged. (e) More information is needed Moreover, the force can be categorized in numerous ways, depending based on classification. For instance, in terms of work, if the job done is positive, then it implies force acting is in a positive direction, and if the work is done is negative, then it means that the object is moving in the opposite direction of the work done It can be stated in words: The net work done on an object is equal to the change in the object's kinetic energy. Notice that we made use of Newton's second law, , where is the net force-the sum of all forces acting on the object. Thus, the work-energy principle is valid only if W is the net work done on the object-that is, the work done by. The net work done on a body is equal to the change in kinetic energy of the body object have the biggest net work done on it by all forces during its motion? A) Free Fall B) Incline C) String D) All the same Negative C) Zero Mechanics Lecture 7, Slide 17. CheckPoint A box sits on the horizontal bed of a movin Hint 3. Find the work done by friction Find , the work done by friction on the block. Express in terms of , , , , and . Hint 1. How to compute work The work done by a force acting along the direction of motion of an object is equal to the magnitude of the force times the distance over which the object moves

### Work-energy theorem Work, energy and power Siyavul

work is done, P= dW dt: (20) Using our general expression for work, we can see that P= d dt Z F~~vdt= F~~v: (21) Because the force acting on an object, along with its velocity, can be functions of time, the power, in general, will also be some function of time. It is equal to the rate of change of the kinetic energy, since we can easily. The object can exist in the region, which is K.E. would become positive. the speed of the trolley will not change. Question 20. A body of mass 0.5 kg travels in a straight line with velocity v = ax 3/2 where a = 5 m _1 /2 s _1. What is the work done by the net force during its displacement from x = 0 to x = 2 m? Answer Object is falling from rest, therefore initial kinetic energy is zero. Once the object hit on the ground, height is zero, therefore no potential energy at ground level. Initial PE = Final KE Impact velocity just before the impact is From work-energy principle, change in the kinetic energy of an object is equal to the net work done on the object   The work done by a system can be easily found by analyzing a graph of force vs displacement. Here is a simple graph for a constant force acting over a distance. The work done is simply the area under the curve of the force/displacement graph. The work done by a 4.0 N force acting over a distance of 6.0 m woul Newton's First Law can also be used to explain the movement of objects travelling with non-uniform motion. This includes situations when the speed, the direction, or both change (B) work done by F. (C) work done by W. (D) the change in momentum of the rock before and after this time. (E) the change in the potential energy of the rock before and after this time. 4. A constant force supplies an average power of 8 W to a box during a certain time interval. If the box has an average speed of 4 m/s and the force acts in the. 1. Point Particle Behavior of a Rigid Object; The relationships derived above for a system of N particles can be generalized for an extended object if the summation over the number of particles is replaced by an integral over the mass.. Comparing the relationship between the net force and the acceleration of the center of mass of an extended object with Newton's second law applied to a point. Q. When you interpret a distance-time graph, the speed of the object is determined by _____. answer choices. looking at the values on the x -axis. looking at the values on the y -axis. finding the length of the graph line. finding the slope of the graph line. Tags: Question 17 parallel to the ramp. So the dot product is zero. 'Work is force times displacement. The work done on Block A is negative, while the work done on Block is positive, because the Since work is force times distance, and the distance the block travels is greager.Ïor Block B, the work done is greater for Block B