Practice Final. A) 0.50 m/s B) 0.2 m/s C) 1.0 m/s D) 1.3 m/s Answer: C

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1 Practice Final 1) Figure represents the position of a particle as it travels along the x-axis. What is the average speed of the particle between t = 2 s and t = 4 s? A) 0.50 m/s B) 0.2 m/s C) 1.0 m/s D) 1.3 m/s 2) Figure above represents the position of a particle as it travels along the x-axis. How does the instantaneous speed of the particle when t = 2 s compare with its speed when t = 4 s? A) The speed at t = 2 s is larger. B) The speed at t = 2 s is smaller. C) They are about equal. D) The speed at t = 4 s is the negative of the speed at t = 2 s. 3) The velocity of a particle as a function of time is given by v(t) = (2.3 m/s) + (4.1 m/s 2 )t - (6.2 m/s 3 )t 2. What is the average acceleration of the particle between t = 1.0 s and t = 2.0 s? A) m/s 2 B) m/s 2 C) 14.5 m/s 2 D) 14.1 m/s 2 4) An astronaut stands by the rim of a crater on the moon, where the acceleration of gravity is 1.62 m/s 2. To determine the depth of the crater, she drops a rock and measures the time it takes for it to hit the bottom. If the depth of the crater is 120 m, how long does it take for the rock to fall? A) 3.04 s B) 12.2 s C) 29.3 s D) 32.1 s 5) Abby throws a ball straight up and times it. She sees that the ball goes by the top of a flagpole after 0.50 s and reaches the level of the top of the pole after a total elapsed time of 4.10 s. What was the speed of the ball at as it passed the top of the flagpole? A) 6.40 m/s

2 B) 16.2 m/s C) 17.6 m/s D) 29.0 m/s 6) To determine the height of a flagpole, Abby throws a ball straight up and times it. She sees that the ball goes by the top of the pole after 0.5 s and then reaches the top of the pole again after a total elapsed time of 4.1 s. How high is the pole above the point where the ball was launched? A) 10 m B) 13 m C) 16 m D) 26 m 7) Refer to Figure 3-4. The sum of these vectors is given by A) 4.2 cm at an angle 180 with respect to +x-axis. B) 4.2 cm along the y-axis. C) 4.2 cm at an angle 270 with respect to +x-axis. D) 4.2 cm along the x-axis. 8) A bullet is fired from ground level with a speed of 150 m/s at an angle 30.0e above the horizontal at a location where g = 10.0 m/s 2. What is the vertical component of its velocity when it is at the highest point of its trajectory? A) 0 m/s B) 75.0 m/s C) 130 m/s D) 150 m/s 9) A child throws a ball with an initial speed of 8.00 m/s at an angle of 40.0e above the horizontal. The ball leaves her hand 1.00 m above the ground. How far from where the child is standing does the ball hit the ground? A) 1.22 m B) 5.14 m C) 6.79 m D) 7.46 m 10) Mary and Debra stand on a snow-covered roof. They both throw snowballs with the same initial speed, but in different directions. Mary throws her snowball downward, at 30e below the horizontal; Debra throws her snowball upward, at 30e. When the snowballs reach the ground below, A) Debra's snowball will stay in the air longer than Mary's.

3 B) Mary's snowball will stay in the air longer than Debra's. C) Both snowballs will take the same amount of time to hit the ground. D) Debra's snowball never hits the ground since it is thrown upwards. 11) A 3.0-kg and a 5.0-kg box rest side-by-side on a smooth, level floor. A horizontal force of 32 N is applied to the 3.0-kg box pushing it against the 5.0-kg box, and, as a result, both boxes slide along the floor. How large is the contact force between the two boxes? A) 12 N B) 20 N C) 32 N D) 0 N 12) You ride on an elevator that is moving downward with constant speed while standing on a bathroom scale. The reading on the scale is A) equal to your true weight, mg. B) more than your true weight, mg. C) less than your true weight, mg. D) could be more or less than your true weight, mg, depending on the value of the speed. 13) A workman lowers a 30.0-kg load using the ideal pulley arrangement shown in Figure 6-1. He allows the rope to slide in his hands, thus exerting a downward force of 100 N on the rope. What is the acceleration of the load? A) 60.0 N B) 1.72 N C) 232 N D) 3.14 N 14) A 3.00-kg mass and a 5.00-kg mass hang vertically at the ends of a rope that goes over an ideal pulley. If the masses are released from rest, how long does it take for the 3.00-kg mass to rise by 1.00 m? A) s B) s C) s D) s 15) A tightrope walker with a mass of 60.0 kg stands at the center of a rope which was initially strung horizontally between two poles. His weight causes the rope to sag symmetrically, making an angle of 4.80 with the horizontal. What is the tension in the rope? A) 359 N B) 589 N C) 2470 N D) 3520 N

4 16) An object is under the influence of a force as represented by the force vs. position graph in Figure 7-4. What is the work done as the object moves from 4 m to 6 m? A) 20 J B) 30 J C) 0 J D) 40 J 17) A 20.0-gram mass is attached to a 120 cm-long string as shown in Figure 6-7. It moves in a horizontal circle with a constant speed of 1.50 m/s. What is the angle a? A) 10.8 B) 13.5 C) 17.7 D) ) A weight of 200 N is hung from a spring with a spring constant of 2500 N/m and lowered slowly. How much will the spring stretch? A) 4.00 cm B) 6.00 cm C) 8.00 cm D) 10.0 cm 19) What is the horsepower needed to change the speed of a 1600-kg sport utility vehicle from 15.0 m/s to 40.0 m/s in 4.00 seconds? A) 369 hp B) 36.9 hp C) 18.8 hp D) 188 hp 20) A 2-kg mass is moving along the x-axis. The potential energy curve as a function of position is shown in Figure The system is conservative. There is no friction. Refer to Figure If the object is at rest at the origin, what will be its speed at 9.0 m along the +x-axis?

5 A) 1.5 m/s B) 2.5 m/s C) 3.5 m/s D) 4.5 m/s 21) A 50.0-kg person stands on a 200-kg raft, which is at rest. She starts to walk on the raft with a speed of 3.00 m/s with respect to the raft. What is the speed of the person relative to the water? A) 2.40 m/s B) m/s C) m/s D) 1.20 m/s 21) A 900-kg car traveling east at 15.0 m/s collides with a 750-kg car traveling north at 20.0 m/s. The cars stick together. In what direction does the wreckage move just after the collision? A) 36.9e N of E B) 42.0e N of E C) 53.1e N of E D) 48.0e N of E 22) A 320-g air track cart traveling at 1.25 m/s collides elastically with a stationary 270-g cart. What is the speed of the 270-g cart after the collision? A) m/s B) m/s C) 1.36 m/s D) 1.14 m/s 23) Three masses are located in the x-y plane as follows: a mass of 6 kg is located at (0 m, 0 m), a mass of 4 kg is located at (3 m, 0 m), and a mass of 2 kg is located at (0 m, 3 m). Where is the center of mass of the system? A) (1 m, 2 m) B) (2 m, 1 m) C) (1 m, 1 m) D) (1 m, 0.5 m) 24) An elastic collision of two objects is characterized by the following. A) Total momentum of the system is conserved. B) Total kinetic energy of the system remains constant. C) Both A and B are true. D) Neither A nor B are true.

6 25) A Ferris wheel with a radius of 16.0 m rotates at a constant rate, completing one revolution in 30.0 s. What is the apparent weight of a 60.0-kg passenger when she is at the bottom of the wheel? A) 589 N B) 562 N C) 631 N D) 852 N 26) A child is riding a merry-go-round, which has an instantaneous angular speed of 1.25 rad/s and an angular acceleration of rad/s 2. The child is standing 4.65 m from the center of the merry-go-round. What is the magnitude of the acceleration of the child? A) 8.05 m/s 2 B) 7.27 m/s 2 C) 2.58 m/s 2 D) 3.46 m/s 2 27) A car is traveling along a highway at 65 mph. What is the linear speed of the bottom of the tires? A) 130 mph B) 0 mph C) 3.0 mph D) 130. mph 28) A solid sphere is rolling without slipping along a horizontal surface with a speed of 5.50 m/s when it starts up a ramp that makes an angle of 25.0e with the horizontal. What is the speed of the sphere after it has rolled 3.00 m up the ramp? A) 4.01 m/s B) 1.91 m/s C) 2.16 m/s D) 3.53 m/s 29) A 15.0-kg child is sitting on a playground teeter-totter, 1.50 m from the pivot. What is the minimum distance, on the other side of the pivot, such that a 220-N force will make the child lift off the ground? A) 1.00 m B) m C) 9.78 m D) 2.35 m 30) A mass of 375 g hangs from a string that is wrapped around the circumference of a pulley with a moment of inertia of kg m 2 and a radius of 26.0 cm. When the mass is released, the mass accelerates downward and the pulley rotates about its axis as the string unwinds. What is the acceleration of the mass? A) 19.9 m/s 2 B) 13.1 m/s 2 C) 6.57 m/s 2 D) 3.28 m/s 2 31) The torque required to turn the crank on an ice cream maker is 4.50 Nm. How much work does it take to turn the crank through 300 full turns? A) 4240 J B) 8480 J C) 1350 J

7 D) 2700 J 32) A solid wood door, 90.0 cm wide by 2.00 m tall has a mass of 35.0 kg. It is ajar and at rest. A ball with a mass of 500 g is thrown perpendicular to the door with a speed of 20.0 m/s and hits the door 60.0 cm from the hinged side. The ball rebounds with a speed of 16.0 m/s along the same line. What is the angular speed of the door after the collision? A) rad/s B) rad/s C) 1.14 rad/s D) 4.57 rad/s 33) A 15.0-kg child is sitting on a playground teeter-totter, 1.50 m from the pivot. What is the minimum distance, on the other side of the pivot, such that a 220-N force will make the child lift off the ground? A) 1.00 m B) m C) 9.78 m D) 2.35 m 34) A child is riding a merry-go-round which completes one revolution every 8.36 s. The child is standing 4.65 m from the center of the merry-go-round. What is the magnitude of the centripetal acceleration of the child? A) 6.84 m/s 2 B) 2.63 m/s 2 C) m/s 2 D) m/s 2 35) Earth circles the sun at a distance of m. What is the magnitude of the centripetal acceleration of Earth in its orbit? A) m/s 2 B) m/s 2 C) m/s 2 D) m/s 2 36) A figure skater is spinning slowly with arms outstretched. She brings her arms in close to her body and her moment of inertia decreases by 1/2. Her angular speed increases by a factor of A) 2. B) 4. C) 2. D) 1/2.