Physics 1401 - Exam 2Chapter 5N-New2. The second hand on a watch has a length of 4.50 mm and makes one revolution in60.00 s. What is the speed of the end of the second hand as it moves in uniform circularmotion?(a) 9.42 10-4 m/s (c) 5.34 10-3 m/s (e) 2.36 10-5 m/s(b) 2.67 10-3 m/s (d) 4.71 10-4 m/s3. Approximately one billion years ago, the Moon orbited the Earth much closer than itdoes today. The radius of the orbit was only 24 400 km. Today, the radius is 385 000 km.The orbital period was only 23 400 s. The present period is 2.36 106 s. Assume that theorbit of the Moon is circular. Calculate the ratio of the speed of the Moon in its ancientorbit to the speed that it has today.(e) 6.39(a) 15.8(c) 10.2(b) 12.8(d) 7.155. A ball is whirled on the end of a string in a horizontal circle of radius R at constantspeed v. The centripetal acceleration of the ball can be increased by a factor of 4 by(a) keeping the speed fixed and increasing the radius by a factor of 4.(b) keeping the radius fixed and increasing the speed by a factor of 4.(c) keeping the radius fixed and increasing the period by a factor of 4.(d) keeping the radius fixed and decreasing the period by a factor of 4.(e) keeping the speed fixed and decreasing the radius by a factor of 4.7. A car traveling at 20 m/s rounds a curve so that its centripetal acceleration is 5 m/s2.What is the radius of the curve?(a) 4 m(c) 80 m(e) 640 m(b) 8 m(d) 160 mReview Exam 2-New.doc-1-

8. A satellite is placed in a circular orbit to observe the surface of Mars from an altitudeof 144 km. The equatorial radius of Mars is 3397 km. If the speed of the satellite is 3480m/s, what is the magnitude of the centripetal acceleration of the satellite?(a) 2.17 m/s2(c) 2.99 m/s2(e) 4.05 m/s2(b) 2.60 m/s2(d) 3.42 m/s211. A boy is whirling a stone around his head by means of a string. The string makes onecomplete revolution every second, and the tension in the string is FT. The boy thenspeeds up the stone, keeping the radius of the circle unchanged, so that the string makestwo complete revolutions every second. What happens to the tension in the sting?(a) The tension is unchanged.(b) The tension reduces to half of its original value.(c) The tension increases to twice its original value.(d) The tension increases to four times its original value.(e) The tension reduces to one-fourth of its original value.14. Sara puts a box into the trunk of her car. Later, she drives around an unbanked curvethat has a radius of 48 m. The speed of the car on the curve is 16 m/s, but the box remainsstationary relative to the floor of the trunk. Determine the minimum coefficient of staticfriction for the box on the floor of the trunk.(a) 0.42(d) 0.33(b) 0.54(e) This cannot be determined without knowing the mass of(c) 0.17 the box.15. In an amusement park ride, a small child stands against the wall of a cylindrical roomthat is then made to rotate. The floor drops downward and the child remains pinnedagainst the wall. If the radius of the device is 2.15 m and the relevant coefficient offriction between the child and the wall is 0.400, with what minimum speed is the childmoving if he is to remain pinned against the wall?(a) 7.26 m/s(c) 12.1 m/s(e) 9.80 m/s(b) 3.93 m/s(d) 5.18 m/sReview Exam 2-New.doc-2-

18. The maximum speed at which a car can safely negotiate an unbanked curve dependson all of the following factors except(a) the diameter of the curve.(b) the acceleration due to gravity.(c) the coefficient of static friction between the road and the tires.(d) the coefficient of kinetic friction between the road and the tires.(e) the ratio of the static frictional force between the road and the tires and thenormal force exerted on the car.20. Determine the minimum angle at which a roadbed should be banked so that a cartraveling at 20.0 m/s can safely negotiate the curve if the radius of the curve is2.00 102 m.(a) 0.200 (c) 11.5 (e) 78.2 (b) 0.581 (d) 19.6 Questions 23 through 25 pertain to the statement below:A 1000-kg car travels along a straight 500-m portion of highway (from A to B) at aconstant speed of 10 m/s. At B, the car encounters an unbanked curve of radius 50 m. Thecar follows the road from B to C traveling at a constant speed of 10 m/s while thedirection of the car changes from east to south.23. What is the magnitude of the acceleration of the car as it travels from A to B?(e) zero m/s2(a) 2 m/s2(c) 10 m/s222(b) 5 m/s(d) 20 m/s24. What is the magnitude of the acceleration of the car as it travels from B to C?(a) 2 m/s2(c) 10 m/s2(e) zero m/s2(b) 5 m/s2(d) 20 m/s225. What is the magnitude of the frictional force between the tires and the road as the carnegotiates the curve from B to C?(a) 20 000 N(c) 5000 N(e) 1000 N(b) 10 000 N(d) 2000 NReview Exam 2-New.doc-3-

26. The earth exerts the necessary centripetal force on an orbiting satellite to keep itmoving in a circle at constant speed. Which statement best explains why the speed of thesatellite does not change although there is a net force exerted on it?(a) The satellite is in equilibrium.(b) The acceleration of the satellite is zero m/s2.(c) The centripetal force has magnitude mv2/r.(d) The centripetal force is canceled by the reaction force.(e) The centripetal force is always perpendicular to the velocity.30. A satellite is placed in equatorial orbit above Mars, which has a radius of 3397 kmand a mass MM 6.40 1023 kg. The mission of the satellite is to observe the Martianclimate from an altitude of 488 km. What is the orbital period of the satellite?(c) 7.36 103 s(e) 7.27 1012 s(a) 9.18 102 s(b) 3.62 103 sd) 1.08 105 s45. A 25-kg box is sliding down an ice-covered hill. When itreaches point A, the box is moving at 11 m/s. Point A is at thebottom of a circular arc that has a radius R 7.5 m. What is themagnitude of the normal force on the box at Point A?(a) 250 N(d) 650 N(b) 280 N(e) 900 N(c) 400 NReview Exam 2-New.doc-4-

Questions 49 through 52 pertain to the situation described below:A 1500-kg car travels at a constant speed of 22 m/s around a circular track that has aradius of 85 m.49. Which statement is true concerning this car?(a) The velocity of the car is changing.(b) The car is characterized by constant velocity.(c) The car is characterized by constant acceleration.(d) The car has a velocity vector that points along the radius of the circle.(e) The car has an acceleration vector that is tangent to the circle at all times.50. What is the magnitude of the acceleration of the car?(a) 5.7 m/s2(c) 9.8 m/s2(e) zero m/s2(b) 0.26 m/s2(d) 1.2 m/s251. What is the average velocity of the car during one revolution?(a) 8.0 m/s(c) 26 m/s(e) zero m/s(b) 12 m/s(d) 44 m/s52. Determine the magnitude of the net force that acts on the car.(a) 390 N(c) 8.5 103 N(e) zero newtons4(b) 1800 N(d) 1.5 10 N53. Jupiter has a mass that is roughly 320 times that of the Earth and a radius equal to 11times that of the Earth. What is the acceleration due to gravity on the surface of Jupiter?(a) 2.7 m/s2(c) 26 m/s2(e) 260 m/s222(b) 9.8 m/s(d) 87 m/sReview Exam 2-New.doc-5-

Physics 1401Chapter 6 Review - Energy1. In which one of the following situations is zero net work done?(a) A ball rolls down an inclined plane.(b) A physics student stretches a spring.(c) A projectile falls toward the surface of Earth.(d) A box is pulled across a rough floor at constant velocity.(e) A child pulls a wagon across a rough surface causing it to accelerate.3. A concrete block is pulled 7.0 m across africtionless surface by means of a rope. Thetension in the rope is 40 N; and the net workdone on the block is 247 J.What angle does the rope make with thehorizontal?(a) 28 (c) 47 (e) 88 (b) 41 (d) 62 6. A force of magnitude 25 N directed at an angle of 37 above the horizontal moves a 10kg crate along a horizontal surface at constant velocity. How much work is done by thisforce in moving the crate a distance of 15 m?(a) zero joules(c) 40 J(e) 300 J(b) 1.7 J(d) 98 JReview Exam 2-New.doc-6-

7. A constant force of 25 N is applied as shownto a block which undergoes a displacement of7.5 m to the right along a frictionless surfacewhile the force acts. What is the work done bythe force?(a) zero joules(b) 94 J(c) 94 J(d) 160 J(e) 160 J11. Which one of the following statements concerning kinetic energy is true?(a) It can be measured in watts.(b) It is always equal to the potential energy.(c) It is always positive.(d) It is a quantitative measure of inertia.(e) It is directly proportional to velocity.15. The kinetic energy of a car is 8 106 J as it travels along a horizontal road. How muchwork is required to stop the car in 10 s?(a) zero joules(c) 8 105 J(e) 8 107 J46(b) 8 10 J(d) 8 10 JReview Exam 2-New.doc-7-

18. A 10.0-g bullet traveling horizontally at 755 m/s strikes a stationary target and stopsafter penetrating 14.5 cm into the target. What is the average force of the target on thebullet?(a) 1.97 104 N(c) 6.26 103 N(e) 3.93 104 N54(b) 2.07 10 N(d) 3.13 10 N22. An elevator supported by a single cable descends a shaft at a constant speed. The onlyforces acting on the elevator are the tension in the cable and the gravitational force.Which one of the following statements is true?(a) The magnitude of the work done by the tension force is larger than that done by thegravitational force.(b) The magnitude of the work done by the gravitational force is larger than that done bythe tension force.(c) The work done by the tension force is zero joules.(d) The work done by the gravitational force is zero joules.(e) The net work done by the two forces is zero joules.24. A 1500-kg elevator moves upward with constant speed through a vertical distance of 25m. How much work was done by the tension in the cable?(a) 990 J(c) 140 000 J(e) 430 000 J(b) 8100 J(d) 370 000 JReview Exam 2-New.doc-8-

26. Two balls of equal size are dropped from the same height from the roof of a building.One ball has twice the mass of the other. When the balls reach the ground, how do thekinetic energies of the two balls compare?(a) The lighter one has one fourth as much kinetic energy as the other does.(b) The lighter one has one half as much kinetic energy as the other does.(c) The lighter one has the same kinetic energy as the other does.(d) The lighter one has twice as much kinetic energy as the other does.(e) The lighter one has four times as much kinetic energy as the other does.28. A woman stands on the edge of a cliff and throws a stone vertically downward with aninitial speed of 10 m/s. The instant before the stone hits the ground below, it has 450 Jof kinetic energy. If she were to throw the stone horizontally outward from the cliff withthe same initial speed of 10 m/s, how much kinetic energy would it have just before ithits the ground?(a) 50 J(c) 450 J(e) 950 J(b) 100 J(d) 800 J30. A block is dropped from a high tower and is falling freely under the influence ofgravity. Which one of the following statements is true concerning this situation? Neglectair resistance.(a) As the block falls, the net work done by all of the forces acting on the block is zerojoules.(b) The kinetic energy increases by equal amounts over equal distances.(c) The kinetic energy of the block increases by equal amounts in equal times.(d) The potential energy of the block decreases by equal amounts in equal times.(e) The total energy of the block increases by equal amounts over equal distances.Questions 37 and 38 pertain to the situation described below:Review Exam 2-New.doc-9-

A 2.0-kg projectile is fired with initial velocity components vox 30 m/s and voy 40 m/sfrom a point on the earth's surface. Neglect any effects due to air resistance.37. What is the kinetic energy of the projectile when it reaches the highest point in itstrajectory?(a) zero joules(b) 900 J(c) 1600 J(d) 2500 J(e) 4900 J38. How much work was done in firing the projectile?(a) 900 J(b) 1600 JReview Exam 2-New.doc(c) 2500 J(d) 4900 J(e) 9800 J- 10 -

39. Two boxes are connected to each other asshown. The system is released from rest andthe 1.00-kg box falls through a distance of1.00 m. The surface of the table is frictionless.What is the kinetic energy of box B just beforeit reaches the floor?(a) 2.45 J(d) 29.4 J(b) 4.90 J(e) 39.2 J(c) 9.80 J42. A bicyclist is traveling at a speed of 20.0 m/s as he approaches the bottom of a hill. Hedecides to coast up the hill and stops upon reaching the top. Determine the verticalheight of the hill.(a) 28.5 m(c) 11.2 m(e) 20.4 m(b) 3.70 m(d) 40.8 m45. An engineer is asked to design a playground slide such that the speed a child reaches atthe bottom does not exceed 6.0 m/s. Determine the maximum height that the slide canbe.(a) 1.8 m(c) 3.2 m(e) 14 m(b) 2.9 m(d) 4.5 mReview Exam 2-New.doc- 11 -

50. The initial velocity of a 4.0-kg box is 11 m/s, due west. After the box slides 4.0 mhorizontally, its speed is 1.5 m/s. Determine the magnitude and the direction of the nonconservative force acting on the box as it slides.(a) 42 N, due west(c) 31 N, due east(e) 83 N, due west(b) 120 N, due east(d) 59 N, due east51. An automobile approaches a barrier at a speed of 20 m/s along a level road. The driverlocks the brakes at a distance of 50 m from the barrier. What minimum coefficient ofkinetic friction is required to stop the automobile before it hits the barrier?(a) 0.4(c) 0.6(e) 0.8(b) 0.5(d) 0.7Review Exam 2-New.doc- 12 -

55. A 51-kg woman runs up a flight of stairs in 5.0 s. Her net upward displacement is 5.0 m.Approximately, what average power did the woman exert while she was running?(a) 5.0 kW(c) 0.75 kW(e) 0.25 kW(b) 1.0 kW(d) 0.50 kW57. An escalator is 30.0 meters long and slants at 30.0 relative to the horizontal. If it movesat 1.00 m/s, at what rate does it do work in lifting a 50.0 kg man from the bottom to thetop of the escalator?(a) 49.3 W(c) 245 W(e) 495 W(b) 98.0 W(d) 292 W59. A warehouse worker uses a forklift to lift a crate of pickles on a platform to a height2.75 m above the floor. The combined mass of the platform and the crate is 207 kg. Ifthe power expended by the forklift is 1440 W, how long does it take to lift the crate?(a) 37.2 s(c) 3.87 s(e) 1.86 s(b) 5.81 s(d) 18.6 sReview Exam 2-New.doc- 13 -

61. The amount on energy needed to power a 0.10-kW bulb for one minute would be justsufficient to lift a 1.0-kg object through a vertical distance of(a) 12 m(c) 100 m(e) 610 m(b) 75 m(d) 120 m62. The graph shows the force component along thedisplacement as a function of the magnitude ofthe displacement. Determine the work done bythe force during the interval from 2 to 10 m.(a) 140 J(b) 190 J(c) 270 J(d) 450 J(e) 560 JReview Exam 2-New.doc- 14 -

67. A motorist driving a 1000-kg car wishes to increase her speed from 20 m/s to 30 m/s in5 s. Determine the horsepower required to accomplish this increase. Neglect friction.(a) 20 hp(c) 70 hp(e) 90 hp(b) 30 hp(d) 80 hpReview Exam 2-New.doc- 15 -

Physics 1401Chapter 7N Review-NewCHAPTER 62. A rock is dropped from a high tower and falls freely under the influence of gravity.Which one of the following statements is true concerning the rock as it falls?(a) It will gain an equal amount of momentum during each second.(b) It will gain an equal amount of kinetic energy during each second.(c) It will gain an equal amount of speed for each meter through which it falls.(d) It will gain an equal amount of momentum for each meter through which it falls.(e) The amount of momentum it gains will be proportional to the amount of potentialenergy that it loses.3. 3. A stunt person jumps from the roof of a tall building, but no injury occurs because theperson lands on a large, air-filled bag. Which one of the following best describes whyno injury occurs?(a) The bag provides the necessary force to stop the person.(b) The bag reduces the impulse to the person.(c) The bag increases the amount of time the force acts on the person and reduces thechange in momentum.(d) The bag decreases the amount of time during which the momentum is changing andreduces the average force on the person.(e) The bag increases the amount of time during which the momentum is changingand reduces the average force on the person.5. A 1.0-kg ball has a velocity of 12 m/s downward just before it strikes the ground andbounces up with a velocity of 12 m/s upward. What is the change in momentum of theball?(e) 24 kg m/s, upward(a) zero kg m/s(c) 12 kg m/s, upward(b) 12 kg m/s, downward (d) 24 kg m/s, downwardReview Exam 2-New.doc- 16 -

9. A 0.065-kg tennis ball moving to the right with a speed of 15 m/s is struck by a tennisracket, causing it to move to the left with a speed of 15 m/s. If the ball remains incontact with the racquet for 0.020 s, what is the magnitude of the average forceexperienced by the ball?(a) zero newtons(c) 160 N(e) 9.8 104 N(b) 98 N(d) 1.6 105 N12. While a car is stopped at a traffic light in a storm, raindrops strike the roof of the car.The area of he roof is 5.0 m2. Each raindrop has a mass of 3.7 10–4 kg and speed of 2.5m/s before impact and is at rest after the impact. If, on average at a given time, 150raindrops strike each square meter, what is the impulse of the rain striking the car?(a) 0.69 N s(c) 0.14 N s(e) 21 N s(b) 0.046 N s(d) 11 N s15. A football player kicks a 0.41-kg football initially at rest; and the ball flies through theair. If the kicker’s foot was in contact with the ball for 0.051 s and the ball’s initialspeed after the collision is 21 m/s, what was the magnitude of the average force on thefootball?(a) 9.7 N(c) 81 N(e) 210 N(b) 46 N(d) 170 NReview Exam 2-New.doc- 17 -

Questions 16 and 17 pertain to the situation described below:A 4.0-kg block slides along a frictionless surface with a constant speed of 5.0 m/s. Twoseconds after it begins sliding, a horizontal, time-dependent force is applied to the mass.The force is removed eight seconds later. The graph shows how the force on the blockvaries with time.16. What is the magnitude of the total impulse of the force acting on the block?(a) 20 N s(b) 42 N s(c) 48 N s(d) 54 N s(e) 60 N s17. What, approximately, is the speed of the block at t 11 seconds?(a) 5.0 m/s(b) 16 m/s(c) 25 m/s(d) 65 m/s(e) 75 m/s21. A 50-kg toboggan is coasting on level snow. As it passes beneath a bridge, a 20-kgparcel is dropped straight down and lands in the toboggan. If (KE)1 is the originalkinetic energy of the toboggan and (KE)2 is the kinetic energy after the parcel has beenadded, what is the ratio (KE)2/(KE)1.(a) 0.4(c) 0.7(e) 1(b) 0.6(d) 0.8Review Exam 2-New.doc- 18 -

Ans. c.25. An 80-kg astronaut carrying a 20-kg tool kit is initially drifting toward a stationaryspace shuttle at a speed of 2 m/s. If she throws the tool kit toward the shuttle with aspeed of 6 m/s as seen from the shuttle, her final speed is(a) 1 m/s toward the shuttle.(d) 4 m/s toward the shuttle.(b) 1 m/s away from the shuttle.(e) 6 m/s away from the shuttle.(c) 2 m/s toward the shuttle.28. Two objects of equal mass traveling toward each other with equal speeds undergo ahead on collision. Which one of the following statements concerning their velocitiesafter the collision is necessarily true?(a) They will exchange velocities.(d) Their velocities will be zero.(b) Their velocities will be reduced.(e) Their velocities may be zero.(c) Their velocities will be unchanged.Review Exam 2-New.doc- 19 -

31. Complete the following statement: Momentum will be conserved in a two-bodycollision only if(a) both bodies come to rest.(b) the collision is perfectly elastic.(c) the kinetic energy of the system is conserved.(d) the net external force acting on the two-body system is zero.(e) the internal forces of the two body system cancel in action-reaction pairs.39. A 50.0-kg boy runs at a speed of 10.0 m/s and jumps onto a cart as shown in the figure.The cart isinitially at rest.If the speed of the cart with the boy on it is 2.50 m/s, what is the mass of the cart?(a) 150 kg(c) 210 kg(e) 300 kg(b) 175 kg(d) 260 kgReview Exam 2-New.doc- 20 -

42. A 35-kg girl is standing near and to the left of a 43-kg boy on the frictionless surface ofa frozen pond. The boy tosses a 0.75-kg ice ball to the girl with a horizontal speed of 6.2m/s. What are the velocities of the boy and the girl immediately after the girl catches theice ball?girlboy(a) 0.81 m/s, left0.67 m/s, right(b) 0.17 m/s, left0.14 m/s, left(c) 0.18 m/s, right0.13 m/s, left(d) 0.42 m/s, left0.49 m/s, right(e) 0.13 m/s, left0.11 m/s, right50. In the game of billiards, all the balls haveapproximately the same mass, about 0.17 kg.In the figure, the cue ball strikes another ballsuch that it follows the path shown. The otherball has a speed of 1.5 m/s immediately afterthe collision. What is the speed of the cueball after the collision?(a) 1.5 m/s(c) 2.6 m/s(e) 5.2 m/s(b) 1.8 m/s(d) 4.3 m/s64. A 100-kg fisherman and a 500-kg supply crate are on a frozen pond that is essentiallyfrictionless. The man and the crate are initially separated by a distance of 600 meters.The fisherman uses a very light rope to pull the crate closer to him. How far has the manmoved when the crate reaches the fisherman?(a) zero meters(c) 50 m(e) 500 m(b) 10 m(d) 100 mReview Exam 2-New.doc- 21 -

Physics 1401Chapter 8 Review2.A wrench is used to tighten a nut as shown inthe figure. A 12-N force is applied 7.0 cmfrom the axis of rotation. What is the torquedue to the applied force?(a) 0.58 N m(b) 0.84 N m(c) 1.71 N m(d) 14 N m(e) 58 N m3. A string is tied to a doorknob 0.79 m from thehinge as shown in the figure. At the instantshown, the force applied to the string is 5.0 N.What is the torque on the door?(a) 3.3 N m(b) 2.2 N m(c) 1.1 N m(d) 0.84 N m(e) 0.40 N mReview Exam 2-New.doc- 22 -

6.A horizontal, 10-m plank weighs 100 N. Itrests on two supports that are placed 1.0m from each end as shown in the figure.How close to one end can an 800-Nperson stand without causing the plank totip?(a) 0 m(d) 0.6 m(b) 0.2 m(e) 0.8 m(c) 0.5 m8.One end of a rope is tied to the handle of ahorizontally-oriented and uniform door. A force F isapplied to the other end of the rope as shown in thedrawing. The door has a weight of 145 N and ishinged on the right. What is the maximum magnitudeof F at which the door will remain at rest?(a) 145 N(d) 424 N(b) 265 N(e) 530 N(c) 381 NReview Exam 2-New.doc- 23 -

10. 10. In the drawing shown, the large wheel has a radius of 8.5m. A rope is wrapped around the edge of the wheel and a7.6 kg-box hangs from the rope. A smaller disk of radius1.9 m is attached to the wheel. A rope is wrapped aroundthe edge of the disk as shown. An axis of rotation passesthrough the center of the wheel-disk system. What is thevalue of the mass M that will prevent the wheel fromrotating?(a) 1.7 kg(d) 34 kg(b) 3.8 kg(e) 46 kg(c) 12 kg14. Consider four point masses located as shown in thesketch. The acceleration due to gravity is the sameeverywhere. What is the x coordinate of the center ofgravity for this system?(a) 2.0 m(c) 3.0 m(e) 3.8 m(b) 2.7 m(d) 3.3 mReview Exam 2-New.doc- 24 -

17. Consider the following four objects:a hoop; a solid sphere; a flat disk; a hollow sphereEach of the objects has mass M and radius R. The axis of rotation passes through thecenter of each object, and is perpendicular to the plane of the hoop and the plane ofthe flat disk. Which object requires the largest torque to give it the same angularacceleration ?(a) the hoop(d) the hollow sphere(b) the flat disk(e) both the solid and the hollow spheres(c) the solid sphere20. A massless frame in the shape of a square with 2-m sideshas a 1-kg ball at each corner. What is the moment ofinertia of the four balls about an axis through the cornermarked O and perpendicular to the plane of the paper?(a) 4 kg m2(b) 8 kg m2(c) 10 kg m2(d) 12 kg m2(e) 16 kg m2Review Exam 2-New.doc- 25 -

22. The drawing shows the top view of a door thatis 2 m wide. Two forces are applied to the dooras indicated. What is the magnitude of the nettorque on the door with respect to the hinge?(a) 0 N m(c) 8.7 N m(e) 26.0 N m(b) 5.0 N m (d) 10.0 N m26. Three children are pulling on a rotatable platform on aplayground. The platform has a radius of 3.65 m. In thepicture, two children are pulling with equal forces of40.0 N in an attempt to make the platform rotateclockwise. The third child applies a force of 60 N asshown. What is the net torque on the platform?Note: “ccw” is counterclockwise and “cw” isclockwise.(a) 73 N m, ccw (c) 511 N m, ccw (e) 0 N m(b) 73 N m, cw(d) 511 N m, cwReview Exam 2-New.doc- 26 -

28. A 45-N brick is suspended by a light string from a 2.0-kgpulley. The brick is released from rest and falls to thefloor below as the pulley rotates through 5.0 rad. Thepulley may be considered a solid disk of radius 1.5 m.What is the angular speed of the pulley?(a) 7.3 rad/s(d) 15 rad/s(b) 8.1 rad/s(e) 17 rad/s(c) 9.4 rad/s31. Consider the following three objects, each of the same mass and radius:(1) a solid sphere (2) a solid disk (3) a hoopAll three are released from rest at the top of an inclined plane. The three objectsproceed down the incline undergoing rolling motion without slipping. In which orderdo the objects reach the bottom of the incline?(a) 1, 2, 3(c) 3, 1, 2(e) All three reach the bottom(b) 2, 3, 1(d) 3, 2, 1 at the same time.34. A 2.0-kg solid cylinder of radius 0.5 m rotates at a rate of 40 rad/s about itscylindrical axis. What power is required to bring the cylinder to rest in 10 s?(a) 20 W(c) 160 W(e) 400 W(b) 40 W(d) 200 WReview Exam 2-New.doc- 27 -

38. A ceiling fan has five blades, each with a mass of 0.34 kg and a length of 0.66 m.The fan is operating in its “low” setting at which the angular speed is 9.4 rad/s. If theblades can be approximated as uniform thin rods that rotate about one end, what isthe total rotational kinetic energy of the five blades?(a) 35 J(c) 23 J(e) 11 J(b) 29 J(d) 17 J41. What happens when a spinning ice skater draws in her outstretched arms?(a) Her angular momentum decreases.(b) Her angular momentum increases.(c) Her moment of inertia decreases causing her to speed up.(d) Her moment of inertia decreases causing her to slow down.(e) The torque that she exerts increases her moment of inertia.644. A 1500-kg satellite orbits a planet in a circular orbit of radius 6.2 10 m. What isthe angular momentum of the satellite in its orbit around the planet if the satellitecompletes one orbit every 1.5 104 s?(a) 3.9 106 kg m2/s(c) 6.2 108 kg m2/s(e) 2.4 1013 kg m2/s142112(b) 1.4 10 kg m /s(d) 8.1 10 kg m /sReview Exam 2-New.doc- 28 -

50. A 3.0-kg ball moves in a straight line at 10 m/s asshown in the figure. At the instant shown, what isits angular momentum about the point P?(a) 30 kg m2/s(b) 90 kg m2/s(c) 120 kg m2/s(d) 150 kg m2/s(e) zero kg m2/sReview Exam 2-New.doc- 29 -

The second hand on a watch has a length of 4.50 mm and makes one revolution in 60.00 s. What is the speed of the end of the second hand as it moves in uniform circular motion? (a) 9.42 10-4 m/s (c) 5.34 10-3 m/s (e) 2.36 10-5 m/s (b) 2.67 10-3 m/s (d) 4.71 10-4 m/s 3. Appr