Term: 161 Thursday, October 27, 2016 Page: 1 *Read the following (20) questions and choose the best answer: 1 The motion of a swimmer during 30.0 minutes workout is represented by the graph below. What is the speed of the swimmer at 2:15 PM? A) Zero. B) 40.0 m/min. C) 120 m/min. D) 279 m/min. 2 Which one of the following is always true about the magnitude of a displacement? A) It is less than or equal to the distance traveled. B) It is greater than the distance traveled. C) It is equal to the distance traveled. D) It is less than the distance traveled.
Term: 161 Thursday, October 27, 2016 Page: 2 3 A motorcyclist traveling at 23 m/s (north) applies the brakes, producing an acceleration of 7.2 m/s 2 (south). What is the motorcyclist's velocity after 2.5 s? A) 5 m/s, north B) 41 m/s, north C) 5 m/s, south. D) 41 m/s, south. 4 A man drives to a town, 120 km away, at an average speed of 60 km/h. He returns at an average speed of 40 km/h. What is his average speed for the entire trip? A) 48 km/h B) 50 km/h C) 65 km/h D) 35 km/h 5 A bus is moving with 80 km/h in front of a car that is moving with 100 km/h. If the distance between the bus and the car is 5 km, how long it takes for the car to reach the bus if their velocities remain unchanged? A) 15 minutes B) 4 hours C) 3 minutes D) 30 minutes
Term: 161 Thursday, October 27, 2016 Page: 3 6 A car, with mass 725 kg, is moving at 120 km/h eastward. In the opposite direction, a truck of mass 2175 kg is moving with 40 km/h. What is the total momentum of the car and the truck? A) Zero B) 48.33 10 3 kg.m/s, eastward. C) 174 10 3 kg.m/s, westward. D) 64.4 10 3 kg.m/s, eastward. 7 A 5-kg box is acted upon by four forces as shown in the figure below, what is the acceleration of the box? A) 6 m/s 2, upward B) 10 m/s 2, upward C) Zero D) 4 m/s 2, downward
Term: 161 Thursday, October 27, 2016 Page: 4 8 The figure below represents the speed-time graph for the motion of a vehicle during a 7.0-minute trip. Which of the following statements is correct about the motion of this vehicle? A) The acceleration of the vehicle has changed several times. B) The acceleration of the vehicle has never changed. C) The vehicle has never accelerated. D) The vehicle has never stopped. 9 If you use a horizontal force of 30 N to slide a sofa across a floor at a constant velocity, what is the sliding friction between the sofa and the floor? A) 30 N. B) Less than 30 N. C) More than 30 N. D) Zero.
Term: 161 Thursday, October 27, 2016 Page: 5 10 Ahmad skydives and parachutes from a stationary helicopter. What is the acceleration of Ahmad when the air resistance equals twice his weight? A) 9.8 m/s 2, upward. B) 9.8 m/s 2, downward. C) 2.0 m/s 2, upward D) 12 m/s 2, downward 11 A rock is dropped at the same instant that a ball at the same height is thrown horizontally. Which of the following statement is correct? (Neglecting air resistance) A) The ball hits the ground with higher speed. B) The rock and the ball hit the ground with equal speed. C) The rock hits the ground with higher speed. D) The rock hits the ground first.
Term: 161 Thursday, October 27, 2016 Page: 6 12 A ball on the end of a string is whirled with constant speed in a counterclockwise horizontal circle. At point A in the circle, the string breaks. Which of the curves sketched below (as seen from above) most accurately represents the path that the ball will take after the string breaks? A) 3 B) 4 C) 2 D) 1 13 A 100-kg man in an elevator is accelerating upward at a rate of 1.0 m/s 2. What is the force pushing upward on the man s feet? A) 1080 N B) 980 N C) 880 N D) 100 N
Term: 161 Thursday, October 27, 2016 Page: 7 14 A 60-kg front-seat passenger in a car moving initially with a speed of 18 m/s is brought to rest by an air bag in a time of 0.4 s. What is the average force acting on the passenger in this process? A) 2,700 N B) 1,080 N C) 150 N D) 45 N 15 A rifle with a mass of 1.2 kg fires a bullet with a mass of 6.0 g (0.006 kg). The bullet moves with a velocity of 600 m/s after the rifle is fired. If external forces acting on the rifle can be ignored, what is the recoil velocity of the rifle? A) 3.0 m/s B) 600 m/s C) 3.6 m/s D) 0.0 m/s 16 Assume you are standing inside an elevator, in which of the following cases your weight will equal zero? A) None of these. B) When the elevator is in free fall. C) When the elevator accelerates upward. D) When the elevator moves with constant velocity.
Term: 161 Thursday, October 27, 2016 Page: 8 17 Assume your mass is m, the mass of Earth is M, and the radius of Earth is R. Which of the following equations represent your weight at Earth s surface? (G is the universal gravitational constant) A) G mm R 2 B) mg C) G M R 2 D) G m R 2 18 Which is true of the force pair of Newton s third law? A) The two forces act on different objects. B) The two forces never produce an acceleration. C) The two forces always cancel each other. D) The two forces are in the same direction. 19 A 1-kg object is moving west at a constant speed of 10 m/s. A force of 100 N, along the east direction, is applied on the object for a time of 0.01 s. The momentum of the object at the end of the 0.01 s interval is A) 9.0 kg.m/s west. B) 9.0 kg.m/s east. C) 1.0 kg.m/s west. D) 11 kg.m/s east.
Term: 161 Thursday, October 27, 2016 Page: 9 20 A ball thrown upward with an initial velocity of 8.30 m/s. Air resistance is negligible. How long will it take to reach the maximum height? A) 0.847 s B) 1.69 s C) 1.18 s D) 2.36 s