55 ILW In Fig, 8-51, a block of mass m 25kg slides head on into a spring of spring constant k 320 N'm. When the block stops, it has compressed the spring by 7.5 cm. The cocfficicnt of ki- netic friction between block and floor is 0.25 While the block is in contact with the spring and being brought to rest, what are (a) the work done by the spring force and (b) the increase in thermal en- ergy of the block-floor system? (c) What is the block's speed just as it reaches the spring? Fig. 8-51 Problem 55

55 ILW In Fig, 8-51, a block of mass m 25kg slides head on into a spring of spring constant k 320 N'm. When the block stops, it has compressed the spring by 7.5 cm. The cocfficicnt of ki- netic friction between block and floor is 0.25 While the block is in contact with the spring and being brought to rest, what are (a) the work done by the spring force and (b) the increase in thermal en- ergy of the block-floor system? (c) What is the block's speed just as it reaches the spring? Fig. 8-51 Problem 55

College Physics

11th Edition

ISBN:9781305952300

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter1: Units, Trigonometry. And Vectors

Section: Chapter Questions

Problem 1CQ: Estimate the order of magnitude of the length, in meters, of each of the following; (a) a mouse, (b)...

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The work done is vertically raising a body of mass M through a distance b is given to be W. If the same body of mass M is raised to the same vertical height b by pulling it up along a horizontal plane. Give observation and conclusion with regards to the result.
An 8.5-kg block is pushed along a horizontal rough surface by a 40-N force inclined at 20° with the horizontal. The coefficient of friction between the surface and block is 0.35. If the block has an initial velocity of 3.6 m/s and the force does 200 J of work on the block, find: Question: The total distance moved by the block.
The crate of mass m= 31 kg is at rest at A on the theta=7o incline. The coefficients of static and kinetic friction between the crate and the incline are mus=0.385 and muk=0.308 (i) Determine whether the crate will slide down the incline or remain at rest at A? (ii) What is the magnitude of the work done by all external forces acting on the crate during its displacement? (iii) Determine the magnitude of the crate’s potential energies at points A and B (iv) What will the crate’s final velocity be? (v) If energy is lost or increased, where did it go?
A vertical spring with constant 41.16 N / m rests in its equilibrium position hanging from the ceiling. On its lower end, a mass of 1.68 kg is hung and it is stretched. When the particle has traveled a distance:0.4 m downward (measured from the equilibrium position), calculate the work done by the spring Wsaring and by the force of gravity WgraVÜty respectively: a) Wing= 3.2928 J and Weravity = -6.5856 J b) Wine=-3.2928 J and Weravity= 6.5856 J c) Wsrine= -3.2928 J and Weravity = -6.5856 J d) Wing= 3.2928 J and Weravity = 6.5856 J
15 O Figure 7-28 shows three forces applied to a trunk that moves leftward by 3.00 m over a friction- less floor. The force magnitudes are F = 5.00 N, F,= 9.00 N, and F3 = 3.00 N, and the indicated angle is 0 = 60.0°. During the displacement, (a) what is the net work done on the trunk by the three forces and (b) does the kinetic energy of the trunk Figure 7-28 Problem 15. increase or decrease?
You are biking along a country road whenyou reach the base of a bridge travelling at 5.00 m/s. At the top of the bridge you have climbed a vertical distance of 5.20 m and have slowed to 1.50 m/s. Ignore any work done by friction or any inefficiency in the bike or your legs. (a) What is the total work done on you and your bike in going from the base of the bridge to its topif the total mass of you and your bike is 80.0 kg? (b)How much work have you done with the force you apply to the pedals?
A crate of mass 9.0 kg is pulled up a rough incline with an initial speed of 1.42 m/s. The pulling force is 110 N parallel to the incline, which makes an angle of 20.6° with the horizontal. The coefficient of kinetic friction is 0.400, and the crate is pulled 4.92 m. (a) How much work is done by the gravitational force on the crate? |-152.68 (b) Determine the increase in internal energy of the crate-incline system owing to friction. 33.02 A careful free-body diagram of the crate may help you determine the magnitude of the friction force. J (c) How much work is done by the 110-N force on the crate? 541.2 (d) What is the change in kinetic energy of the crate? 355.5 You appear to have calculated the change in kinetic energy correctly using your incorrect results from the previous parts. J (e) What is the speed of the crate after being pulled 4.92 m? 9 You appear to have calculated the speed correctly using your incorrect result from part (d). m/s
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24 O In Fig. 7-33, a horizontal force F, 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 fric- tionless ramp at angle e= 30.0°. (a) During the displacement, what is the net work done on the book by F, the gravi- tational force on the book, and the nor- Pachoy mal force on the book? (b) If the book has zero kinetic energy at the start of the displacement, what is its speed at the end of the displacement? Figure 7-33 Problem 24.
For example, the truck in Fig. 7-14 exerts a force F on the trailing load, which as velocity v at some instant. The instantaneous power due to F is the rate at vhich F does work on the load at that instant and is given by Eqs. 7-47 and 7-48. Saying that this power is "the power of the truck" is often acceptable, but keep in mind what is meant: Power is the rate at which the applied force does work. A Checkpoint 3 A block moves with uniform circular motion because a cord tied to the block is an- chored at the center of a circle. Is the power due to the force on the block from the cord positive, negative, or zero?