Activity 5. A block of wood with mass = 2.4 kg moves in a straight line on a frinctionless horizontal surface. Its initial speed is 3.5 m/s and then pushed 4.2 m in the direction of the initial velocity by a 12-N force. (a) Use the work-energy theorem to calculate the wood's final speed. (b) Calculate the acceleration produce by the force. 1+1 WORK

Activity 5. A block of wood with mass = 2.4 kg moves in a straight line on a frinctionless horizontal surface. Its initial speed is 3.5 m/s and then pushed 4.2 m in the direction of the initial velocity by a 12-N force. (a) Use the work-energy theorem to calculate the wood's final speed. (b) Calculate the acceleration produce by the force. 1+1 WORK

Name: Activity 5. A block of wood with mass = 2.4 kg moves in a straight li
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Description: Activity 5. A block of wood with mass = 2.4 kg moves in a straight line on afrinctionless horizontal surface. Its initial speed is 3.5 m/s and then pushed4.2 m in the direction of the initial velocity by a 12-N force. (a) Use thework-energy theorem

University Physics Volume 1

18th Edition

ISBN:9781938168277

Author:William Moebs, Samuel J. Ling, Jeff Sanny

Publisher:William Moebs, Samuel J. Ling, Jeff Sanny

Chapter7: Work And Kinetic Energy

Section: Chapter Questions

Problem 66P: A sled stalls from rest at the top of a snow-covered incline that makes a 22 angle with the...

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A child of mass m starts from rest and slides without friction from a height h along a curved waterslide (Fig. P5.46). She is launched from a height h/5 into the pool. (a) Is mechanical energy conserved? Why? (b) Give the gravitational potential energy associated with the child and her kinetic energy in terms of mgh at the following positions: the top of the waterslide, the launching point, and the point where she lands in the pool. (c) Determine her initial speed V0 at the launch point in terms of g and h. (d) Determine her maximum airborne height ymax in terms of h, g, and the horizontal speed at that height, v0x. (e) Use the x-component of the answer to part (c) to eliminate from the answer to part (d), giving the height ymax in terms of g, h, and the launch angle . (f) Would your answers be the same if the waterslide were not frictionless? Explain. Figure P5.46
Give an example of something think of as work in everyday circumstances that is not work in the scientific sense. Is energy transferred or changed in form in your example? If so, explain how this without doing work.
A student expends 7.5 W of power in lifting a textbook 0.50 m in 1.0 s with a constant velocity. (a) How much work is done, and (b) how much does the book weigh (in newtons)? The answers to Confidence Exercises may be found at the back of the book.
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Two blocks, A and B (with mass 50.0 kg and 1.00 102 kg, respectively), are connected by a string, as shown in Figure P5.86. The pulley is frictionless and of negligible mass. The coefficient of kinetic friction between block A and the incline is k = 0.250. Determine the change in the kinetic energy of block A as it moves from to , a distance of 20.0 m up the incline (and block B drops downward a distance of 20.0 m) if the system starts from rest. Figure P5.86
Grains from a hopper falls at a rate of 10 kg/s vertically onto a conveyor belt that is moving horizontally at a constant speed of 2 m/s. (a) What force Is needed to keep the conveyor belt moving at the constant velocity? (b) What is the minimum power of the motor driving the conveyor belt?
A child of mass m starts from rest and slides without friction from a height h along a curved waterslide (Fig. P5.46). She is launched from a height h/5 into the pool. (a) Is mechanical energy conserved? Why? (b) Give the gravitational potential energy associated with the child and her kinetic energy in terms of mgh at the following positions: the top of the waterslide, the launching point, and the point where she lands in the pool. (c) Determine her initial speed V0 at the launch point in terms of g and h. (d) Determine her maximum airborne height ymax in terms of h, g, and the horizontal speed at that height, v0x. (e) Use the x-component of the answer to part (c) to eliminate from the answer to part (d), giving the height ymax in terms of g, h, and the launch angle . (f) Would your answers be the same if the waterslide were not frictionless? Explain. Figure P5.46
(a) How long will it take an 850-kg car with a useful power output of 40.0 hp (1hp=746W) to reach a speed of 15.0 m/s, neglecting friction? (b) How long will this acceleration take if the car also climbs a 3.00-m-high hill in the process?
A sled stalls from rest at the top of a snow-covered incline that makes a 22 angle with the horizontal. After sliding 75 m down the slope, its speed is 14 m/s. Use the work-energy theorem to calculate the coefficient of kinetic friction between the runners of the sled and the snowy surface.
A car accelerates uniformly from rest. Ignoring air friction, when does the car require the greatest power? (a) When the car first accelerates from rest, (b) just as the car reaches its maximum speed, (c) when the car reaches half its maximum speed. (d) The question is misleading because the power required is constant. (e) More information is needed.
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Suppose that the sled plus passenger of the preceding problem is pushed 20 m across the snow at constant velocity by a force directed 30 below the horizontal. Calculate (a) the work of the applied force, (b) the work of fiction, and (c) the total work.