Problem 1RCQ: Which has greater momentum: an automobile at rest or a moving skateboard? Problem 2RCQ: When a ball is hit with a given force, why does contact over a long time impart more speed to the... Problem 3RCQ: Why is it a good idea to extend your bare hand forward when you are getting ready to catch a... Problem 4RCQ: Why is it poor judgment to have the back of your hand up against the outfield wall when you catch a... Problem 5RCQ: Why is it advantageous, in karate, to apply a force for a short time? Problem 6RCQ Problem 7RCQ: If a ball has the same speed just before being caught and just after being thrown, in which case... Problem 8RCQ: In which of cases (1), (2), and (3) in Question 7 is the greatest impulse required? Problem 9RCQ: What does it mean to say that momentum (or any quantity) is conserved? Problem 10RCQ: When a cannonball is fired, momentum is conserved for the system of cannon + cannonball. Would... Problem 11RCQ: Railroad car A rolls at a certain speed and makes a perfectly elastic collision with car B of the... Problem 12RCQ: If the equally massive railroad cars of Question 11 couple together after colliding inelastically,... Problem 13RCQ: When is energy most evident? Problem 14RCQ: Cite an example in which a force is exerted on an object without doing work on the object. Problem 15RCQ: Which requires more work: lifting a 50-kg sack a vertical distance of 2 m or lifting a 25-kg sack a... Problem 16RCQ: A car is raised a certain distance in a service station lift and therefore has potential energy... Problem 17RCQ: Two cars are raised to the same elevation on service station lifts. If one car is twice as massive... Problem 18RCQ: If a moving car speeds up until it is going three times as fast as it was, how much kinetic energy... Problem 19RCQ: What is the relationship between work and power? Problem 20RCQ: What is the relationship between the gain in kinetic energy and the work when work is done? Problem 21RCQ: Compared with the work that the brakes must supply to stop a car moving at some original speed, how... Problem 22RCQ: What will be the kinetic energy of the ram of a pile driver when it suddenly undergoes a 10-kJ... Problem 23RCQ: An apple hanging from a limb has potential energy because of its height. If the apple falls, what... Problem 24RCQ: Can a machine multiply input force? Input distance? Input energy? (If your three answers are the... Problem 25RCQ: If a machine multiplies force by a factor of 4, what other quantity is diminished, and by how much? Problem 26RCQ: What is the efficiency of a machine that miraculously converts all the input energy to useful output... Problem 27RCQ: What becomes of energy when efficiency is lowered in a machine? Problem 28RCQ: What is the ultimate source of the energy supplied by fossil fuels, dams, and windmills? Problem 29RCQ: What is the ultimate source of geothermal energy? Problem 30RCQ: Can we correctly say that hydrogen is a relatively new source of energy? Why or why not? Problem 35PAC: Show that the momentum for a 2-kg brick parachuting straight downward at a constant speed of 8 m/s... Problem 36PAC: Show that the impulse on a baseball that is hit with 100 N of force in a time of 0.5 s is 50 N.s. Problem 37PAC: Show that when a 10-kg cart undergoes a 2.0-m/s increase in speed, the impulse on the cart is 20 N ... Problem 38PAC: Show that when an impulse produced by a 12-N force acts over 2.0 s on an ice puck initially at rest... Problem 39PAC: Show that 2.4 J of work is done when a force of 2.0 N moves a book 1.2 m. (1 N1 m = 1 J) Problem 40PAC: Calculate the work done when a 20-N force pushes a cart 3.5 m. Problem 41PAC: Show that when a 3.0-kg book is lifted 2.0 m, its increase in gravitational potential energy is 60... Problem 42PAC: Show that the gravitational potential energy of a 1000-kg boulder raised 5 m above ground level is... Problem 43PAC: Show that the kinetic energy of a 1.0-kg book tossed across the room at a speed of 3.0 m/s is 4.5 J.... Problem 44PAC: Calculate the kinetic energy of a 84-kg scooter moving at 10 m/s. Problem 45PAC: Show that 24 J of work is done when a 3.0-kg block of ice is moved from rest to a speed of 4.0 m/s. Problem 46PAC: Show that a 2,500,000-J change in kinetic energy occurs for an airplane that is moved 500 m in... Problem 47PAC: Show that 50 W of power is required to give a brick 100 J of PE in a time of 2 s. Problem 48PAC: Show that nearly 786 W of power is expended when a 500-N barbell is lifted 2.2 m above the floor in... Problem 49PAC: Show that the efficiency of a machine that has an input of 100 J and an output of 40 J is 0.40. Problem 50TAS: In Chapter 1 we learned that acceleration a=vt, and in Chapter 2 we learned that the cause of... Problem 51TAS: A 10-kg bag of groceries is tossed onto a table at 3 m/s and slides to a stop in 2 s. Begin with the... Problem 52TAS: An ostrich egg of mass m is tossed at a speed v into a sagging bed sheet and is brought to test in a... Problem 53TAS: A 6-kg bail rolling at 3 m/s bumps into a pillow and stops in 0.5 s. (a) Show that the force exerted... Problem 54TAS: At a baseball game, a ball of mass m = 0.15 kg moving at a speed v = 30 m/s is caught by a fan. (a)... Problem 55TAS: Jeannie Beanie (mass 40 kg), standing on slippery ice, catches her leaping dog, Daisy (mass 20 kg),... Problem 56TAS: A railroad diesel engine weighs four times as much as a freight car. The diesel engine coasts at 5... Problem 57TAS: A 5-kg fish swimming at 1 m/s swallows an absent-minded 1-kg fish swimming toward it at a velocity... Problem 58TAS: Little Hudson (next page) holds the 10-kgbarbell 0.3 m above the floor. (a) What is the PE of the... Problem 59TAS: It you push a crate horizontally with a force of 100 N across a 10-m factory floor, and the friction... Problem 60TAS: A simple lever is used to lift a heavy load. When a 60-N force pushes one end of the lever downward... Problem 61TAS: The following questions refer to Problem 60: (a) How much work is done by the 60-N force? (b) What... Problem 62TAS: In raising a 6000-N piano with a pulley system, the movers note that for every 2 m of rope pulled... Problem 63TAS: The girl steadily pulls her end of the rope upward a distance of 0.4 m with a constant force of 50... Problem 64TAS: How many watts of power do you expend when you exert a force of 6 N that moves a book 2 m in a time... Problem 65TAS: Show that 480 W of power is expended by a weightlifter who lifts a 60-kg barbell a vertical distance... Problem 66TAS: When an average force F is exerted over a certain distance on a shopping cart of mass m, its kinetic... Problem 67TAS: Emily holds a banana of mass m over the edge of a bridge of height b. She drops the banana, and it... Problem 68TAS: Starting from rest, Megan Zooms down a frictionless slide from an initial height of 4.0 m. Show that... Problem 69TAR: The balls have different masses and speeds. Rank the following from greatest to least: (a) Momentum,... Problem 70TAR: Jogging Jake runs along a train flatcar that moves at the velocities shown. In each case, Jakes... Problem 71TAR: Starting from rest, Marshall pushes crates across the floor of his classroom tor 3 seconds with a... Problem 72TAR: A ball is released from rest at the left of the metal track shown. Assume it has only enough... Problem 73TAR: The roller coaster ride starts from rest at point A. Rank, from greatest to least, the following... Problem 74TAR: Rank the scale readings from greatest to least. (Ignore friction.) Problem 75E: A lunar vehicle is tested on Earth at a speed of 12 km/h. When it travels at that same speed on the... Problem 76E: In terms of impulse and momentum, why do airbags in cars reduce the chances of injury in accidents? Problem 77E: Why are todays autos designed to crumple upon impact? Problem 78E: If you throw a raw egg against a wall, youll break it; but if you throw it with the same speed into... Problem 79E: In terms of impulse and momentum, when a boxer is being hit, why is it important that he or she move... Problem 80E: To throw a ball, do you exert an impulse on it? Do you exert an impulse to catch it if its traveling... Problem 81E: Bronco dives from a hovering helicopter and finds his momentum increasing. Does this violate the... Problem 82E: A pair of skaters who are initially at rest push against each other so that they move in opposite... Problem 83E: When you are traveling in your car at highway speed, the momentum of a bug is suddenly changed as it... Problem 84E: You are at the front of a floating canoe near a dock. You leap, expecting to land on the dock... Problem 85E: If you throw a ball horizontally while standing on a skateboard, you roll backward with a momentum... Problem 86E: A fully dressed person is at rest in the middle of a pond on perfectly frictionless ice and must get... Problem 87E Problem 88E: In the previous chapter, rocket propulsion was explained in terms of Newtons third law. That is, the... Problem 89E: When vertically falling sand lands in a horizontally moving cart, the cart slows. Ignore any... Problem 90E: In a movie, the hero jumps straight down from a bridge onto a small boat that continues to move with... Problem 91E: Freddy Frog drops vertically from a tree onto a horizontally moving skateboard. The skateboard... Problem 92E: If your friend pushes a stroller four times as far as you do while exerting only half the force,... Problem 93E: Which requires more work: stretching a strong spring a certain distance or stretching a weak spring... Problem 94E: Two people of the same weight climb a flight of stairs. The first person climbs the stairs in 30 s,... Problem 95E: Why do you run out of breath when running up the stairs not when walking up the stairs? Problem 96E: A friend says that when twice as much works is done on a wagon, it will gain twice as much kinetic... Problem 97E: Compared with a pickup truck moving at a certain speed and braking to a stop, how much work must the... Problem 98E: When a cannon with a long barrel is fired, the force of expanding gases acts on the cannonball for a... Problem 99E: At what point in its motion is the KE of a pendulum bob at a maximum? At what point is its PE at a... Problem 100E: A physics instructor demonstrates energy conservation by releasing a heavy pendulum bob, at shown,... Problem 101E: On a playground slide, a child has potential energy that decreases by 1000 J while her kinetic... Problem 102E: Consider the identical balls released from rest on tracks A and B, as shown. When they reach the... Problem 103E Problem 104E: In the absence of air resistance, a snowball thrown vertically upward with a certain initial KE... Problem 105E: Youre on a rooftop and you throw one snowball down-ward to the ground below and another upward. The... Problem 106E: When a driver applies the brakes 10 keep a car going down-hill at constant speed and constant... Problem 107E: When the mass of a moving object is doubled, with no charge in speed, by what factor is its momentum... Problem 108E: When the velocity of an object it doubled, by what factor is its momentum changed? By what factor is... Problem 109E: Which, if either, has greater momentum a 1-kg ball moving at 2 m/s or a 2-kg ball moving at 1 m/s?... Problem 110E: If an objects kinetic energy is zero, what is its momentum? Problem 111E: If your momentum is zero, is your kinetic energy necessarily zero also? Problem 112E: Two lumps of clay with equal and opposite momenta have a head on collision and come to rest. Is... Problem 113E: Consider Charlottes swinging-balls apparatus. If two balls are lifted and released, momentum is... Problem 114E: Discuss the physics that explains how the girl in Figure 3.29 can jack up a car while applying so... Problem 115E: Why bother using a machine if it cannot multiply work input to achieve greater work output? Problem 116E: In the pulley system shown, Block A has a mass of 10 kg and is suspended precariously at rest.... Problem 117E: If an automobile had a 100% efficient engine, transfer-ring all of the fuel's energy to work, would... Problem 118E: The energy we need to live comes from chemically stored potential energy in food, which is... Problem 119E: To combat wasteful habits, we often speak of "conserving energy" by turning off lights, heating or... Problem 120E: What is the argument that dry-rock geothermal power is a form of nuclear power? Problem 121E: What is the argument that the energy provided by a hydrogen fuel cell is actually solar energy? Problem 122E: What is the fuel that power a fuel cell in forklifts, busses, and trains? Problem 123E Problem 124DQ: Railroad cars are loosely coupled so that there is a noticeable delay between the time the first car... Problem 125DQ: Your friend says that the law of momentum conservation is violated when a ball rolls down a hill and... Problem 126DQ: An ice sailcraft is stalled on a frozen lake on a windless day. The skipper sets up a fan as shown... Problem 127DQ: Will your answer to Question 126 be different if the air is brought to a halt by the sail without... Problem 128DQ: Discuss the advisability of simply removing the sail in the situation discussed in Questions 126 and... Problem 129DQ: Suppose that three astronauts outside a spaceship decide to play catch. All three equally Strong... Problem 130DQ: Discuss whether something can have energy without having momentum. Discuss whether something can... Problem 131DQ: Arrange the following four energy-transforming devices or processes in the correct order for... Problem 132DQ: What are the roles of water, energy, hydrogen, and oxygen in (a) electrolysis, (b) operation or a... Problem 133DQ: Does a car burn more fuel when its lights are turned on? Does the overall consumption of fuel depend... Problem 134DQ: This may seem like an easy question for a physics buff to answer: With what force does a 10-N rock... Problem 135DQ: Your friend says that one way to improve air quality in a city is to synchronize traffic lights so... Problem 136DQ: Does the electric power produced by wind-powered generators affect the speed of the wind? That is,... Problem 137DQ: A red ball of mass m and a blue ball of mass 2m have the same kinetic energy. Explain which of the... Problem 138DQ: No work is done by gravity on a bowling ball resting or moving on a bowling alley, because the force... Problem 139DQ: Consider a bob attached by a stringa simple pendulumthat swings to and fro. (a) Why does the tension... Problem 140DQ: Consider a satellite in a circular orbit above Earth's surface. In Chapter 4 we will learn that the... Problem 1RAT: A freight train rolls along a track with considerable momentum, If it then rolls at the same speed... Problem 2RAT: In the absence of external forces, momentum is conserved in (a) an elastic collision. (b) an... Problem 3RAT: If the running speed of Fast Freda doubles, what also doubles is her (a) momentum. (b) kinetic... Problem 4RAT: Which of the following equations best illustrate s the usefulness of automobile airbags? (a) F = ma... Problem 5RAT: Which of the following equations is most useful for solving a problem that asks for the distance... Problem 6RAT: How much work is done on a 200-kg crate that is hoisted 2 m in a time of 4 s? (a) 400J (b) 1000J (c)... Problem 7RAT: A circus diver drops from a high pole into water far below. When he is halfway down, (a) his... Problem 8RAT: A bicycle that travels twice as fast as another when braking to a stop will skid (a) twice as far.... Problem 9RAT: A bicycle that travels twice as fast as another when braking to a stop will skid (a) twice as far.... Problem 10RAT: A machine cannot multiply (a) force. (b) distance. (c) energy. (d) none of these; that is, it can... format_list_bulleted