1. A stone falls from a platform 18 m high. When will it hit the ground? (a) 1.74 s (b) 1.83 s (c) 1.92 s (d) 2.01 s

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1 1. A stone falls fom a platfom 18 m high. When will it hit the gound? (a) 1.74 s (b) 1.83 s (c) 1.9 s (d).01 s Constant acceleation D = v 0 t + ½ a t. Which, if any, of these foces causes the otation of the Eath? (a) The foce of gavity (b) The foce of angula momentum (c) The foce of inetia (d) No foce Law of Inetia 1 3. A ca acceleates away fom a stop sign at 6.7 m/s. Afte 4.5 seconds the speed of the ca is (a) 60.3 m/s (b) 15.1 m/s (c) 30. m/s (d) 67.8 m/s Constant acceleation v = v 0 + a t 4. A ca acceleates away fom a stop sign at 6.7 m/s. Afte 4.5 seconds the distance fom the stop sign is (a) 60.3 m (b) 15.1 m (c) 30. m (d) 67.8 m Constant acceleation D = v 0 t + ½ a t 1

2 Constant velocity v = v 0 D = v 0 t velocity at time t distance at time t Constant acceleation v = v 0 + a t D = v 0 t + ½ a t velocity at time t distance at time t Pove it: The aveage velocity is ½ (v 0 + v); Then the distance is D = aveage velocity x time D = ½ (v 0 + v 0 + at) x t D = v 0 t + ½ a t 3 5. A pendulum bob is pulled ove to a point (B) whee the height of the bob is m above the lowest point (A) in the pendulum s swing. The bob is eleased fom est at B. What is the speed of the bob as it passes the point A? (a) 3.13 m/s (b) 3.91 m/s (c) 4.69 m/s (d) 6.6 m/s Enegy is conseved ½ m v + m g y = constant 6. A block slides without fiction down an incline and onto a hoizontal floo. The initial speed is 3 m/s and the initial height on the incline is m above the floo. What is the speed of the block afte it eaches the floo? (a) 5. m/s (b) 6.95 m/s (c) 6.00 m/s (d) 8.69 m/s Enegy is conseved ½ m v + m g y = constant 4

3 Consevation of enegy When the action of a foce changes the kinetic enegy of an object, ½ m v + V(x) = ½ m v + V(x ) beginning state ending state 5 7. Both electic powe and steam ae geneated at the MSU Powe Plant. What is the pimay enegy souce? (a) Coal and liquid oxygen (b) Coal and nuclea (c) Coal and atmospheic oxygen (d) Coal alone Buning of coal is a chemical eaction 8. What total enegy is used to light a 75 watt light bulb fo 5 minutes? (a) J (b) W (c) 375 W (d) 375 J Powe = ate of enegy usage 6 3

9. In a head-on collision between a small ca and a lage tuck, (a) the foce on the ca is geate than the foce on the tuck. thid law (b) the foce on the ca is smalle than the foce on the tuck.

4 9. In a head-on collision between a small ca and a lage tuck, (a) the foce on the ca is geate than the foce on the tuck. thid law (b) the foce on the ca is smalle than the foce on the tuck. (c) the foce on the ca is equal to the foce on the tuck. (d) thee ae no foces involved, but the two vehicles cannot occupy the same space. 10. In a head-on collision between a small ca and a lage tuck, (a) the change of velocity of the ca is geate than the change of velocity of the tuck. (b) the change of velocity of the ca is smalle than the change of velocity of the tuck. (c) the change of velocity of the ca is equal to the change of velocity of the tuck. (d) the change of velocity cannot be defined. second law 11. In a head-on collision between a small ca and a lage tuck, (a) the foce on the ca dive is geate than the foce on the tuck dive. (b) the foce on the ca dive is smalle than the foce on the tuck dive. (c) the foce on the ca dive is equal to the foce on the tuck dive. (d) the foces on the dives ae the same as the foces on the vehicles. 7 Newton s thid law Fo evey action thee is an equal but opposite eaction. equal stengths opposite diections Ca-tuck collision: F tuck = F ca a tuck < a ca because a=f/m 8 4

5 1. A submaine is 3 kilometes ( = 3000 m) below the suface of the ocean. What is the pessue on the hull? (Density of sea wate = 105 kg/m 3.) (a) Pa (b) Pa (c) Pa (d) Pa p(d) = p(0) + ρ g d 13. A ping-pong ball is placed in an inveted funnel, and a stong cuent of ai is blown downwad though the stem of the funnel. What happens? (a) The ball falls out of the funnel by gavity. (b) The ball is pushed out of the funnel by the pessue of the ai cuent. (c) The ball comes out of the funnel because of both gavity and the pessue of the cuent. (d) The ball stays up in the funnel. You saw it youself! I assume that you know whethe a block of wood (white pine) will float o sink in wate. Now, compae the volume of 1 kg of wood to the volume of 1 kg of wate. (a) The volumes ae equal. (b) The volume of the wate is lage. (c) The volume of the wood is lage. (d) Moe infomation is needed. Achimedes 15. At what depth is the pessue of wate in a lake equal to 4 atm? (1 atm = N/m ) (a) 31.0 m (b) 7.0 m (c) 3.0 m (d) 19.0 m p(d) = p(0) + ρ g d 10 5

6 Pessue vesus depth in a fluid [ p(d) p(0) ] A = ρ Ad g (Achimedes Pinciple) p(d) = p(0) + ρ g d What is the weight of a 8 kg mass nea the suface of the Eath? (a) 78 newtons (b) 8 newtons (c) 8 kg (d) 16 pounds weight = foce of gavity W = m g 17. A dive slams on the bakes and the ca sceeches to a stop. The initial speed is 55 mi/h = 4 m/s; the time to stop is.7 s. What is the foce on the dive if his mass is 75 kg? (a) 347 N (b) 736 N (c) 667 N (d) 990 N F = m a = m v/ t 1 6

7 Equivalent vaiations of Newton s second alw F = m a a = F/m m = F/a given m, a : calculate F given F, m : calculate a given F, a : calculate m Conside the kickoff in a football game. Which statement is false? (a) The kicke's foot exets a foce on the ball. (b) The ball exets a foce on the kicke's foot. (c) The foce on the ball is geate than the foce on the kicke's foot. (d) The kicke's foot undegoes an acceleation. thid law 19. A hockey playe hits a slap shot and the puck slides towad the goal. While the puck is sliding towad the goal, the foces that ae affecting its motion ae (a) the foce of the slap and a small foce of fiction. (b) the foce of inetia and a small foce of fiction. (c) a small foce of fiction. (d) the foce of gavity and a small foce of fiction. fist law 14 7

8 Newton s thid law Fo evey action thee is an equal but opposite eaction. Wheneve two objects inteact, the foces ae equal in stength and opposite in diection. Newton s fist law (law of inetia) An object in motion emains in motion. It doesn t equie a foce to keep it moving! So Aistotle was wong Who discoveed that foces always occu in pais? (a) Aistotle (b) Galileo thid law (c) Newton (d) Huygens 1. A mable is launched at high speed fom point P on a hoizontal cicula tack; the tack goes thee-fouths of the way aound a cicle. The mable olls aound the tack and then onto a hoizontal table at point Q. Which dashed cuve descibes the subsequent motion of the mable? A B C D fist law 16 8

9 . A bowle olls a ball towad the bowling pins. As it olls down the bowling lane, what foce causes the fowad motion of the bowling ball? (a) The push it was given by the hand of the bowle. (b) The gavitational foce that pulled the bowle's am down as he am swung fowad. (c) The bowle's feet pushed back on the Eath and the ball moves fowad because of the eaction by Newton's thid law. (d) Thee is no fowad foce on the ball. fist law The semi-majo axis of the Eath's obit is 1 AU and the peiod of evolution of the Eath is 1 y. (Note: AU = astonomical unit; y = yea.) The semi-majo axis of the obit of Mas is 1.5 AU. What is the peiod of evolution of Mas? (a) 0.5 months (b) 1.5 months (c).5 months (d) 3.5 months Keple s thid law T a 3 4. A child whose mass is 5 kg is iding on a playgound mey-go-ound, holding onto the hand holds. The adius of the mey-go-ound is = 4 m and the peiod of otation is T = 3 s. How much foce must the child exet to stay on the mey-go-ound? (a) 379 N (b) 399 N (c) 419 N (d) 439 N centipetal acceleation a = v / 18 9

10 5. Heny Cavendish measued the Newtonian gavitational constant G in It was then possible to calculate the mass (M) of the Eath. Which fomula would give the mass M? (R = adius of the Eath) (a) M = gr/g (b) M = GR/g GMm (c) M = gr /G = and (d) M = GR /g F F = ma 6. Of those listed, which planet is moving fastest? (a) Venus (b) Mas GMm (c) Jupite = (d) Eath F and F = ma The obits of Eath and Jupite ae appoximately cicula. The adius of Jupite's obit is appoximately 5 times geate than that of Eath's obit. Compae the speeds of Jupite and Eath. (a) The speed of Eath is 5 times geate than that of Jupite. (b) The speed of Eath is about two and a quate times geate. (c) The speeds ae equal. (d) The speed of Eath is only 1/5 as lage as that of Jupite. 8. How many times will Eath cicle the sun while Jupite cicles the sun once? (The adius of Jupite's obit is 5. times that of Eath's obit.) (a) a little moe than 10 times (b) a little moe than 11 times (c) a little less than 1 times (d) appoximately 5 times GMm F = and F = ma Keple s thid law T a

11 Newton s deivation of Keple s thid law ma = F v m GMm = Note : v π = T v 4π T GM = F T 4π = GM Why is Michigan colde in Januay than July? (a) The Eath is fathe fom the sun in Januay. (b) The Eath is close to the sun in July. (c) The Eath is close to the sun in Januay. (d) The Eath's axis of otation is not pependicula to the plane of the obit. (e) Cold ai flows fom south to noth in Januay. The easons fo seasons 30. What is the venal equinox? (a) The day when the Eath's axis is pependicula to the plane of the obit. (b) The day when the Eath's axis is paallel to the plane of the obit. (c) The day when the Eath's axis ceases to tilt away fom the sun and begins to tilt towad the sun. (d) The day when the Eath's axis ceases to tilt towad the sun and begins to tilt away fom the sun. The easons fo seasons 11

12 The easons fo seasons 1. The axis of otation is constant (consevation of angula momentum).. The Eath tavels aound the sun on an appoximately cicula obit. 3. The axis of otation is tilted fom the pependicula. 3 1

Chapter 5: Uniform Circular Motion

Chapter 5: Uniform Circular Motion Chapte 5: Unifom Cicula Motion Motion at constant speed in a cicle Centipetal acceleation Banked cuves Obital motion Weightlessness, atificial gavity Vetical cicula motion Centipetal Foce Acceleation towad