Momentum - 5 Steps to a 5 500 AP Physics Questions to Know by Test Day

5 Steps to a 5 500 AP Physics Questions to Know by Test Day (2012)

Chapter 5. Momentum

121. A 70-kg man runs at a constant velocity of 2 m/s. What is his momentum?

(A) 35 kg m/s

(B) 68 kg m/s

(D) 72 kg m/s

(E) 140 kg m/s

122. A 10-N force is applied to a hockey puck over a period of 0.1 s. What is the change in momentum of the hockey puck?

(A) 1.0 kg m/s

(B) 9.9 kg m/s

(D) 10.1 kg m/s

(E) 100 kg m/s

123. A 1,000-kg car moving at a constant velocity of 11.0 m/s strikes a concrete barrier and comes to a complete stop in 2.0 s. What is the force acting on the car?

(A) −5,500 N

(B) −180 N

(D) 180 N

(E) 5,500 N

124. A 1.0-kg ball moving at 10 m/s strikes a wall and bounces back. The collision is perfectly elastic. What is the ball’s momentum after the collision? (Assume a frictionless surface.)

(A) −100 kg m/s

(B) −10 kg m/s

(D) 10 kg m/s

(E) 100 kg m/s

125. A 10-kg box is sliding across an ice rink at 10 m/s. A skater exerts a constant force of 10 N against it. How long will it take for the box to come to a complete stop?

(A) 0.5 s

(B) 1.0 s

(D) 50 s

(E) 100 s

126. Two balls of equal mass collide in a perfectly elastic collision. Ball A moves to the right at 10 m/s. Ball B moves to the left at 5 m/s. After the collision, Ball B moves to the right at 3 m/s. What is the velocity of Ball A after the collision? (Assume a frictionless surface.)

(A) −10 m/s

(B) −8.0 m/s

(D) 2 m/s

(E) 3 m/s

127. A 140-kg fullback is running with the football at 10 m/s. A 70-kg defender runs at him in the opposite direction at 5 m/s. The defender wraps his arms around the fullback. What is the velocity of the two players after the collision? (Assume a frictionless surface.)

(A) −10 m/s

(B) −5 m/s

(D) 5 m/s

(E) 10 m/s

128. There are two billiard balls each with a mass of 200 g. A pool player shoots Ball A with a velocity of 1.0 m/s at Ball B, which is at rest. After the collision, Ball A stops and Ball B travels off in a straight line. What is the velocity of Ball B after the collision? (Assume a frictionless surface.)

(A) −1.0 m/s

(B) −0.2 m/s

(D) 0.2 m/s

(E) 1.0 m/s

129. A bullet has a mass of 50 g and its momentum is 25 kg m/s. What is the velocity of the bullet?

(A) 2 × 10⁻³ m/s

(B) 5 × 10⁻¹ m/s

(D) 5 × 10¹ m/s

(E) 5 × 10² m/s

130. [For Physics C Students Only] Two objects are moving around a fixed reference point. Object 1 is located at 2.0 m (x₁) and has a mass (m₁) of 10 kg. Object 2 is located at 6.0 m (x₂) and has a mass (m₂) of 20 kg. Where is the center of mass of the system?

(A) 2.1 m

(B) 4.0 m

(D) 5.0 m

(E) 5.9 m

131. A 150-kg halfback is running down the field carrying the ball at a velocity of 5 m/s. A 50-kg receiver from the opposing team is running at him in the opposite direction. The receiver hopes to tackle and stop him in an inelastic collision. Will the receiver be able to stop him? And, if so, at what velocity must he run?

(A) Yes, −15 m/s

(B) Yes, −10 m/s

(D) Yes, 0 m/s

(E) No, the receiver cannot stop the fullback

132. A batter applies a constant force of 10.0 N over a period of 5 m/s when he strikes a baseball. The mass of the baseball is 145 g. What is the change in velocity of the baseball?

(A) 0.100 m/s

(B) 0.345 m/s

(D) 2.00 m/s

(E) 2.90 m/s

133. What is the momentum of an electron moving at 90 percent of the speed of light?

(A) 3.3 × 10⁻³¹ kg.m/s

(B) 2.5 × 10⁻³¹ kg.m/s

(D) 2.5 × 10⁻²² kg.m/s

(E) 3.3 × 10⁻²⁰ kg.m/s

134. A 260-g cue ball moving at 1.0 m/s strikes a 150-g numbered ball at rest. The collision is elastic and the cue ball stops. What is the velocity of the numbered ball?

(A) 0.6 m/s

(B) 1.2 m/s

(D) 1.7 m/s

(E) 2.0 m/s

135. A 750-kg aircraft is flying level at 100 m/s. A tailwind blows for 2 min and the aircraft’s speed increases to 120 m/s. What was the force of the tailwind?

(A) 125 N

(B) 250 N

(D) 5,000 N

(E) 7,500 N

136. [For Physics C Students Only] This graph depicts the motion of a box being pushed across the floor. Which of the following statements describes the force upon the box?

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(A) The force on the box is a constant 0.5 N.

(B) The force on the box is a constant 1 N.

(D) The force on the box is 1 N and increasing.

(E) The force on the box is 2 N and increasing.

137. A force of 2.0 N exerted on an object for 100 m/s increases the object’s velocity by 1.0 m/s. What was the mass of the object?

(A) 0.1 kg

(B) 0.2 kg

(D) 20 kg

(E) 200 kg

138. A 70-kg stuntman free falls from a building for 5 s and hits an air bag. The air bag exerts a force on him over a time period of 2.5 s and he comes to a complete stop. What was the force exerted by the air bag?

(A) 100 N

(B) 275 N

(D) 875 N

(E) 1,000 N

139. Two railroad cars (2 × 10⁴ kg each) are traveling in the same direction along a railroad track. Car A is traveling at 14 m/s, and Car B is traveling at 10 m/s. The two cars collide. What will the velocity of the combined cars be after the collision?

(A) 10 m/s

(B) 12 m/s

(D) 20 m/s

(E) 24 m/s

140. [For Physics C Students Only] This graph depicts the motion of a box being pushed across the floor. Which of the following statements describes the force upon the box?

images

(A) The force on the box is constant.

(B) The force on the box is decreasing at a constant rate.

(D) The acceleration of the box is constant.

(E) The force on the box is zero.

141. Two skaters, a 70-kg man and a 50-kg woman, are skating on an ice rink. They “push off” from each other and move in opposite directions. After the push off, the woman moves with a velocity of 2.5 m/s. What is the velocity of the man?

(A) −2.5 m/s

(B) −1.8 m/s

(D) 0 m/s

(E) 2.5 m/s

142. To have a momentum of 10 kg.m/s, at what velocity must a 0.5-kg object be traveling?

(A) 1.0 m/s

(B) 5.0 m/s

(D) 20 m/s

(E) 50 m/s

143. A cue ball with a mass of 250 g travels at 1.0 m/s and hits a numbered ball with a mass of 170 g at rest. The numbered ball moves off at an angle of 45°, while the cue ball moves off at an angle of −45°. At what velocities do the balls move?

(A) The cue ball and the numbered ball move at 1.0 m/s.

(B) The cue ball moves at 1.0 m/s, and the numbered ball moves at −1.0 m/s.

(D) The cue ball moves at 1.04 m/s, and the numbered ball moves at −1.04 m/s.

(E) The cue ball moves at 0.71 m/s, and the numbered ball moves at 1.04 m/s.

144. A 2,000-kg airplane flies at 343 m/s. What is its momentum?

(A) 0.17 kg.m/s

(B) 5.8 kg.m/s

(D) 6.9 × 10⁴ kg.m/s

(E) 6.9 × 10⁵ kg.m/s

145. A marksman fires a 7.5-g bullet from a 1.2-kg handgun. The bullet travels away at 365 m/s. At what velocity does the handgun recoil?

(A) −2.4 m/s

(B) −1.2 m/s

(D) 1.2 m/s

(E) 2.4 m/s

146. Two air cars weighing 500 g each are on a frictionless track. Car A is moving at 0.2 m/s when it collides into Car B at rest. The two cars get stuck together. At what velocity will the combined cars move?

(A) −0.1 m/s

(B) −0.05 m/s

(D) 0.05 m/s

(E) 0.1 m/s

147. A rifle fires a 4.0-g bullet at a velocity of 950 m/s. If the bullet is in the rifle barrel for only 0.1 s, what force does the rifle exert on the bullet?

(A) 18 N

(B) 28 N

(D) 48 N

(E) 58 N

148. A 1,000-kg cannon fires a 15-kg cannon ball. The cannon is mounted on a carriage that allows it to recoil at −1.5 m/s. What is the velocity of the cannon ball?

(A) 10 m/s

(B) 50 m/s

(D) 200 m/s

(E) 500 m/s

149. A cue ball with a mass of 250 g travels at 1.0 m/s and hits a numbered ball with a mass of 170 g at rest. The numbered ball moves off at an angle of 30°, while the cue ball moves off at an angle of −60°. At what velocities do the balls move? (Show your work.)

150. An 800-kg car is traveling along a wet road at a velocity of 25.5 m/s. A 1,000-kg car is traveling along the same road in the same direction at 34.7 m/s. The two cars collide and lock together. Answer the following questions. (Show your work.)

(a) The two interlocked cars proceed at what velocity after the collision?

(b) If the coefficient of -kinetic friction between the tires of the cars and the wet pavement is 0.7, what is the force of friction?