Number 18 KE -5nvV5 Ho hmuch work was done to change her speed?VS. Now what is her kinetic energy?KE- C45)5)562.53)562.5=11687.5)Z258.10 Shawn and his bike have a total mass of 45.0-kg. Shawn rides 1800 m in 600 seconds at n constantvelocity. What is Shawn's kinetic energy?1800=606 -3KEKE 5)()11. Matt and Will each have a mass of 60-kg and they are moving together with a velocity of 10.0 m/s.What is their combined kinețic energy?n=60 KKE = (60) Clo)?కెలంబుV=l0.0m/s12. A 2000-kg car has a velocity of 12.0 m/s. The car then hits a tree. The tree doesn't move and the carcomes to rest.a. Find the change in kinetic energy of the car.n-2000 Kv= 17.6 n/sb. Find the amount of work done in pushing in the front of the car.KE-mv? KE-(2000)(:0-4370Jc. Find the size of the force that pushed in the front of the car in 0.50 m.13. How much potential energy does Tim, mass 60.0-kg, gain when he climbs a gymnasium rope a distancem= b6 of 3,5 m?GPE=nnghGPE = (60) (9.8).5)=9= 9.8ト=)514. A 6.4-kg bowling ball is lifted 2.1 m into a storage rack. Calculate the increase in the ball's potential2058.5energy.m=6.4 99 = 9.815. Mary weighs 500-N and walks down a flight of stairs to a level 5.50 m below her starting point. What isthe change in Mary's potential energy?E= 500 NGPE = mghGPE = (6.4) (9.8) (2-1) =131.712(500) (5.50)=2750J16. Å weightlifter raises a 180-kg barbell to a height of 1.95 m. What is the increase in the barbell'spotential energy? m =180 Kgg-9.8h-1.98GPE = mghOPE = C180)(9.8) (1.98) = 3492.72J17. A 10.0-kg rocket is fired vertically from Cape Canaveral. Its fuel gives it a kinetic energy of 1960 J bythe time the rocket motor burns out of fuel. What additional height will the rocket rise?18. A hallway of energy is constructed. People are told that to do 1.00 J of work, they should pull on a ropethat lifts a block 1.00 m. What should be the mass of the block?

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Answered: 18. A hallway of energy is constructed.…

18. A hallway of energy is constructed. People are told that to do 1.00 J of work, they should pull on a rope that lifts a block 1.00 m. What should be the mass of the block?

Physics for Scientists and Engineers with Modern Physics

10th Edition

ISBN:9781337553292

Author:Raymond A. Serway, John W. Jewett

Publisher:Raymond A. Serway, John W. Jewett

Chapter7: Energy Of A System

Section: Chapter Questions

Problem 25P: Review. You can think of the workkinetic energy theorem as a second theory of motion, parallel to...

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Review. You can think of the workkinetic energy theorem as a second theory of motion, parallel to Newtons laws in describing how outside influences affect the motion of an object. In this problem, solve parts (a), (b), and (c) separately from parts (d) and (e) so you can compare the predictions of the two theories. A 15.0-g bullet is accelerated from rest to a speed of 780 m/s in a rifle barrel of length 72.0 cm. (a) Find the kinetic energy of the bullet as it leaves the barrel. (b) Use the workkinetic energy theorem to find the net work that is done on the bullet. (c) Use your result to part (b) to find the magnitude of the average net force that acted on the bullet while it was in the barrel. (d) Now model the bullet as a particle under constant acceleration. Find the constant acceleration of a bullet that starts from rest and gains a speed of 780 m/s over a distance of 72.0 cm. (e) Modeling the bullet as a particle under a net force, find the net force that acted on it during its acceleration. (f) What conclusion can you draw from comparing your results of parts (c) and (e)?