College Physics Chapter 6 Alan Giambattista Betty Richardson Robert Richardson 4th edition Chapter 6 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Question 1 Two water balloons are thrown from a window with the same speed but balloon 1 is thrown straight up while balloon 2 is thrown straight out. Which one has the highest speed on impact? (Ignore friction) A) balloon 1 B) balloon 2 C) both have the same speed D) need to know the masses

Question 2 A water balloon of mass 280 g is thrown straight up in the air from ground level with an initial speed of 3.0 m/s. Which of the following are possible values for its kinetic energy as it flies through the air? A) 1.3 kg·m/s2 B) -1.3 kg·m/s2 C) 2.6 kg·m/s2 D) all are possible values

Question 3 The moon revolves around the earth in a circular orbit. Does Earth do work on the Moon ? A) Yes, it does positive work. B) Yes, it does negative work. C) No, it does no work at all.

Question 4 Planet Xavier has a moon, Yakov, which orbits in a highly elliptical orbit? At which point does Xavier’s gravity do work on the moon? B A) A B) B C) C D) Gravity never does work on an orbiting moon. C A

Question 5 Compare the kinetic energy of two balls: ball 1: mass m thrown with speed 2v ball 2: mass 2m thrown with speed v A) KE1 = 4KE2 B) KE1 = KE2 C) 2KE1 = KE2 D) KE1 = 2KE2

Question 6 A box with mass m1 is being pulled up a rough incline by a rope-pulley-weight system. How many forces are doing work on the box? A) one force B) two forces C) three forces D) four forces E) no forces are doing work

Question 7 A cart starts with velocity v and rolls up the path shown. At what point is the kinetic energy greatest? A) 1 B) 3 C) 2 D) 4

Question 8 At what point does the cart have the greatest total energy? B) 2 C) 3 D) 4 E) all the same

Question 9 Can the total mechanical energy E = K + U ever be negative ? A) Yes, always. B) Yes, because K can be negative. C) Yes, because U can be negative. D) No.

Question 10 A truck, initially at rest, rolls down a frictionless hill and attains a speed of 20 m/s at the bottom. To achieve a speed of 40 m/s at the bottom, how many times higher must the hill be? A) half the height B) the same height C) 12 times the height D) twice the height E) four times the height

Question 11 Dr. Evil is fleeing Secret Agent 009 up a mountain road when a lucky shot takes out his brakes. He attempts to slow by driving up an incline but can't stop before driving off a cliff and crashing at the bottom of a ravine. Correctly order the transformation of energy in this scenario. A) chemical -> kinetic -> potential -> kinetic -> acoustic+heat B) acoustic -> chemical -> kinetic -> potential -> kinetic -> heat C) kinetic -> potential -> kinetic -> chemical -> acoustic+heat D) potential -> kinetic -> chemical -> kinetic -> acoustic+heat

Question 12 Your brakes can apply a constant force, F, to the wheels of your car. If it takes a distance of 30 m to stop when you are traveling 40 km/hr, what distance is required to stop when you are traveling 120 km/hr? A) 10 m B) 90 m C) 110 m D) 270 m

Question 13 A force of 5 N is applied to the end of a spring, and it stretches 10 cm. How much farther will it stretch if an additional 2.5 N of force are applied? A) 2.5 cm B) 5 cm C) 10 cm D) 15 cm

Question 14 A spring is compressed a distance x give a rocket an initial velocity v. To double the initial speed of the rocket, the spring should be compressed a distance ______. A) 1/2 x B) x C) xÖ 2 D) 2x E) 4x

Question 15 A ball of mass m is held a distance h above a table top. The top of the table is a distance 2h above the floor. What is the gravitational potential energy of the ball with respect to the table? A) mgh B) 2mgh C) 3mgh

Question 16 Two forces are applied over a distance x as shown in the graph at right. F1 is constant over the distance, but F2 varies from zero to 2F1. Compare the work done by the two forces. A) W1 > W2 B) W1 = W2 C) W1 < W2

Question 17 A chocolate candy bar contains 290 Calories. To what height would you have to lift a 2000-kg car to store an equivalent amount of energy? A) 6.2 cm B) 31 m C) 62 m D) 610 m

Question 18 Suppose that a given amount of work is required to crush an aluminum can and you can crush a can by dropping a rock on it from height h on the Earth. On the moon, from what height must you drop the same rock to crush a can? A) h B) 3h C) 6h D) 9h

Question 19 Suppose that you can crush an aluminum can by dropping a rock of mass m on it from a height h. Which of the following scenarios would crush two cans? A) dropping a rock of mass 2m from height h B) dropping a rock of mass m from height 2h C) dropping a rock of mass 1/2m from height 4h D) all of the above E) none of the above

Question 20 What power must an engine have if it is to be used to raise a 25-kg load 10 m in 4 seconds? A) 25 W B) 625 W C) 1000 W D) 2500 W

Answer Key – Chapter 6 C A B D E A D B C