Put me in Coach
1. Question:
The long heavy tail of a spider monkey enables the monkey to easily vary its...
Answer: Center of gravity.
2. Question:
Based on stability concepts, you would expect a very broad tree to have...
Answer: A very broad root system.
3. Question:
When you carry a heavy load with one arm, why do you tend to hold your free arm away from your body?
Answer: To change the center of gravity of your body and the load.
4. Question:
You push a table tennis ball beneath the surface of water in a glass of water. The center of gravity of the ball...
Answer: Neither rises nor falls.
5. Question:
Nellie Newton swings a rock into a circular path while holding an attached string overhead. The string makes a 45-degree angle to the vertical (comprising a "conical pendulum"). The centripetal force that holds the rock in its circular path is...
Answer: The horizontal component of the string tension.
6. Question:
Where is the center of gravity of a softball bat located?
Answer: In the more massive end of the bat.
7. Question:
Suzie Spacewalker hovers in space beside a rotating space station in outer space. Both she and the center of mass of the space station are at relative rest. If the space station is in Earth orbit, then Suzie...
Answer: Is also in Earth orbit.
8. Question:
If you try to touch your toes while standing flat against a wall, you probably will fall over. The reason this happens is that...
Answer: Your center of gravity is not located above your support area.
9. Question:
What is the direction of the force that acts on clothes in the spin cycle of a washing machine?
Answer: Outward.
10. Question:
An object will fall over if its center of gravity is...
Answer: Not over its area of support.
11. Question:
A ball resting on the floor is in what kind of equilibrium?
Answer: Neutral.
12. Question:
A ladybug rests on the bottom of a tin can that is being whirled horizontally on the end of a string. Since the ladybug, like the can, moves in a circle, there must be a force on it. What exerts this force?
Answer: The string.
13. Question:
A possible space habitat of the future is a cylinder in space rotating about its long axis. What is the relative gravitational field along the axis of the habitat?
Answer: Zero.
14. Question:
Which has greater angular speed, a horse near the outside rail of a merry-go-round or a horse near the inside rail?
Answer: Neither—they both have the same angular speed.
15. Question:
A person weighs less at the equator than at the poles. The reason for this has to do with the...
Answer: Spin of the Earth.
16. Question:
A car travels in a circle with constant speed. The net force on the car...
Answer: Is directed toward the center of the curve.
17. Question:
A tin can whirled on the end of a string moves in a circle because...
Answer: There is an inward force acting on the can.
18. Question:
Which has greater linear speed, a horse near the outside rail of a merry-go-round or a horse near the inside rail?
Answer: The outside horse.
19. Question:
When a wrench is slid spinning over a frictionless tabletop, its center of gravity follows...
Answer: A straight-line path with regular speed.
20. Question:
In which of the following is the center of gravity located at a point where there is no mass?
Answer: Donut.
21. Question:
An object thrown into the air with a spin rotates about its...
Answer: Center of gravity.
22. Question:
People in the future may well live inside a rotating space structure that is more than 2 km in diameter. In the structure, people on the inside of the outer edge will experience 1 g while people halfway to the axis will experience...
Answer: 1/2 g.
23. Question:
If an object is in stable equilibrium, any displacement will...
Answer: Raise its center of gravity.
24. Question:
The centripetal force exerted on stunt motorcyclist Biker Bob while riding on the inner vertical surface of a circular track is...
Answer: The normal force.
Question:
As an object falls freely in a vacuum, its...
Answer: Velocity increases.
Question:
If a freely falling object were somehow equipped with a speedometer, its speed reading would increase each second by...
Answer: About 10 m/s.
Question:
Suppose an object is in free fall. Each second the object falls...
Answer: A larger distance than in the second before.
Question:
If a projectile is fired straight up at a speed of 10 m/s, the total time to return to its starting point is about...
Answer: 2 seconds.
Question:
When a basketball player jumps to make a shot, once the feet are off the floor, the jumper's acceleration...
Answer: Is g; no more, no less.
Question:
When you look at the speedometer in a moving car, you can see the car's...
Answer: Instantaneous speed.
Question:
One possible unit of speed is...
Answer: All of the above (kilometers per hour, miles per hour, light years per century).
Question:
A ball is thrown straight up. At the top of its path, its instantaneous speed is...
Answer: 0 m/s.
Question:
A freely falling object starts from rest. After falling for 9 seconds, it will have a speed of about...
Answer: 90 m/s.
Question:
Consider drops of water leaking from a water faucet. As the drops fall, they...
Answer: Get farther apart.
Question:
A minivan starts from rest, and after 9 seconds, it is moving at 27 m/s. What is the minivan's average acceleration?
Answer: 3 m/s².
Question:
If you drop a feather and a coin at the same time in a tube filled with air, which will reach the bottom of the tube first?
Answer: The coin.
Question:
Acceleration is defined as the change in...
Answer: Velocity divided by the time interval.
1. Question:
A ball tossed vertically upward rises, reaches its highest point, and then falls back to its starting point. During this time, the acceleration of the ball is always...
Answer: Directed downward.
2. Question:
A car travels 15 meters in the first second of travel, 15 meters again during the second second of travel, and 15 meters again during the third second. Its acceleration is...
Answer: 0 m/s².
3. Question:
A ball is thrown straight up. At the top of its path, its acceleration is...
Answer: About 10 m/s².
4. Question:
A ball is thrown upwards and caught when it comes back down. In the absence of air resistance, the speed of the ball when caught would be...
Answer: The same as the speed it had when thrown upwards.
5. Question:
Suppose you are in a car that is going around a curve. The speedometer reads a constant 30 miles per hour. Which of the following is NOT true?
Answer: Your velocity is constant.
1. Question:
The horizontal component of a projectile's velocity is independent of...
Answer: The vertical component of its velocity.
2. Question:
At what part of a path does a projectile have minimum speed?
Answer: At the top of its path.
3. Question:
A cannon with a barrel velocity of 100 m/s launches a cannonball horizontally from a tower. Neglecting air resistance, how far vertically will the cannonball have fallen after 3 seconds?
Answer: 45 m.
4. Question:
An airplane flying into a headwind loses ground speed, and an airplane flying with the wind gains ground speed. If an airplane flies at right angles to the wind, then ground speed is...
Answer: More.
5. Question:
A soccer ball is kicked at some angle into the air. In the first second, it moves 15 meters horizontally. Assuming it doesn't hit the ground and air resistance is negligible, how far does it move horizontally in the next second?
Answer: 15 m.
6. Question:
After a rock that is thrown straight up reaches the top of its path and is starting to fall back down, its acceleration is (neglecting air resistance)...
Answer: The same as when it was at the top of its path.
1. Question:
You could throw a baseball horizontally at a speed of 8 km/s, and if there were no air drag and nothing could stop it, it would...
Answer: Escape Earth's atmosphere.
2. Question:
In Chapter 2, you learned about "hang time," the time a jumper's feet are off the ground in a vertical jump. If the jumper runs horizontally and has the same vertical component of takeoff velocity, hang time will be...
Answer: No different.
3. Question:
A scalar is a quantity that has...
Answer: Magnitude.
4. Question:
In order to find the components of a vector, you should...
Answer: All of the above (draw the vector with correct magnitude and orientation, measure the sides of the rectangle, draw a rectangle so that the vector is the diagonal).
5. Question:
At the instant a ball is thrown horizontally with a large force, an identical ball is dropped from the same height. Which ball hits the ground first?
Answer: Neither—they both hit the ground at the same time.
6. Question:
When in orbit, a satellite such as the space shuttle is...
Answer: Simply a projectile.
7. Question:
A ball is thrown straight upward at 10 m/s. Ideally (no air resistance), the ball will return to the thrower's hand with a speed of...
Answer: 10 m/s.
8. Question:
A cannonball is launched horizontally from a tower. If the cannon has a barrel velocity of 90 m/s, where will the cannonball be 1 second later? (Neglect air resistance.)
Answer: 90 m downrange.
Question:
An object is dropped and falls freely to the ground with an acceleration of g. If it is thrown upward at an angle instead, its acceleration would be...
Answer: g downward.
2. Question:
What is the resultant of a 15-unit vector and a 20-unit vector at right angles to each other?
Answer: 25 units.
3. Question:
In the absence of air resistance, the angle at which a thrown ball will go the farthest is...
Answer: 45 degrees.
4. Question:
Suppose a small plane can fly at 240 km/h relative to the surrounding air. Suppose also that there is a 60 km/h tailwind. How fast does the plane's shadow move across the ground?
Answer: 300 km/h.
5. Question:
A ball is thrown horizontally from the top of a tall cliff. Neglecting air drag, what vertical distance has the ball fallen 1.0 second later?
Answer: 5 meters.
6. Question:
Michael throws a ball horizontally from the top of a building that is 5 m high. He hopes the ball will reach a swimming pool that is at the bottom of the building, 8.0 m horizontally from the edge of the building. If the ball is to reach the pool, with what initial speed must Michael throw it with?
Answer: 8m/sq
7. Question:
When an object reachesterminal velocity, its acceleration is...
Answer: 0 m/s².
5. Question:
A push on a 4-kilogram brick accelerates the brick. Neglecting friction, to equally accelerate a 16-kilogram brick, one would have to push...
Answer: With 4 times as much force. (Using F=maF=ma, the force needed is proportional to the mass.)
6. Question:
you pull horizontally on a desk with a force of 150 N and the desk doesn't move, the friction force must be
Answer: 200 N.
3. Question:
Suppose a cart is being moved by a force. If suddenly a load is dumped into the cart so that the cart's mass doubles, what happens to the cart's acceleration?
Answer: It halves.
4. Question:
As a care package falls from a high-flying stationary helicopter, its velocity increases and its acceleration...
Answer: decreaaes.
5. Question:
How much force is needed to accelerate a 4.0-kg physics book to an acceleration of 3.0 m/s²?
Answer: 12.0 N.
6. Question:
If the force acting on a cart doubles, what happens to the cart's acceleration?
Answer: It doubles.
7. Question:
A force of 6 N accelerates a mass of 6 kg at the rate of 1 m/s². The acceleration of a mass of 12 kg acted upon by a force of 12 N is...
Answer: The same.
Question:
You pull horizontally on a 50-kg crate with a force of 450 N and the friction force on the crate is 250 N. The acceleration of the crate is...
Answer: 4m/s
2. Question:
A rock is thrown vertically into the air. At the very top of its trajectory, the net force on it is...
Answer: Its weight. (At the top of the trajectory, gravity is the only force acting on the object, so the net force is equal to its weight.)
3. Question:
Which of the following would exert the most pressure on the ground?
Answer: A woman standing in high-heel shoes. (Pressure is calculated as P=F/AP=F/A, and high-heel shoes have a smaller contact area, which increases pressure.)
4. Question:
A 15-N falling object encounters 7 N of air resistance. The magnitude of the net force on the object is...
Answer: 8 N. (The net force is Fnet=Fgravity−Fair resistance=15 N−7 N=8 NFnet=Fgravity−Fair resistance=15N−7N=8N).
5. Question:
The reason a tennis ball and a solid steel ball will accelerate at the same rate, in the absence of air resistance, is that...
Answer: The force acting on them is the same. (In the absence of air resistance, all objects experience the same acceleration due to gravity, regardless of mass.)
6. Question:
Suppose a particle is accelerated through space by a constant 10-N force. Suddenly the particle encounters a second force of 10-N in a direction opposite to that of the first force. The particle...
Answer: Continues at the speed it had when it encountered the second force. (The net force is zero, so the particle will continue with constant velocity, according to Newton's first law.)
7. Question:
An apple weighs 1 N. The net force on the apple when it is in free fall is...
Answer: 1 N. (In free fall, the only force acting on the apple is its weight, so the net force is equal to its weight.)
7. Question: a 8n falling object encounters 8N of air resistance the magnitude of the net force onthe object is
Answer: 0n
8.Question:you are on a frozen pond and the ice starts to crack if you lie down on the ice and begin to crawl this will
Answer: decrease pressure on the ice
9.Question: a car has a mass of 2500kg and accelerate at 3m/s squared, what is the magnitude of the force acting on the car
Answer: 7500n
Question:Torque is defined as...
Answerforce times lever arm.
Question:Suppose you try loosening a nut with a wrench, and the nut doesn't give at all. You increase your chance of success if you ___.
Answer Have a friend help you pull on the wrench,Be sure to exert force perpendicular to the lever arm, Exert a larger force, and Extend the lever arm.
Question:If a football is kicked so the force on the ball is through its center of gravity, the ball will ___.
Answermove without any tumbling or spinning.
Question:Which has more rotational inertia, a bicycle wheel or a solid disk of the same mass and diameter?
Answerthe wheel.
Question:Which has more rotational inertia, a girl running with her legs bent or the same girl running with her legs straight?
Answerwith straight legs.
Question:Which objects roll down an incline with the greatest acceleration?
Answerobjects with small rotational inertia.
Question:Any solid cylinder will roll down an incline with greater acceleration than any hollow cylinder if the ___.
AnswerNONE OF THE ABOVE ARE NECESSARY.
Question:A person's rotational inertia is least about ___.
Answerthe person's longitudinal axis.
Question:When a gymnast moves from an extended position to a tucked position, she ___.
Answerdecreases her rotational inertia.
Question:When an ice skater pulls in his hands to turn faster ____.
AnswerAngular momentum mush be conserved.His moment of inertia changes.His rotational speed changes.
Question:Two people sit on a balanced seesaw. When one person leans toward the center of the seesaw, the person on the end of the seesaw will ____.
Answer rise.
Question:To turn a stubborn screw, it is best to use a scewdriver that has a _____.
Answerwide handle.
Suppose a carnival Ferris Wheel has seats that are lovated halfway between the center and the outside rim. Compared to the ordinary Ferris Wheel, where the seats are on the outside rim, your rotational speed on this Ferris Wheel would be ____.
Answerthe same.
Question:Which rolls to the bottom of a hill sooner, a car tire alone or the same tire mounted on a rim?
Answerthe mounted tire, regardless of its weight.
Question:A ring and a disk roll down a hill together. Which reaches the bottom first?
Answerthe disk.
Question:At the health spa, Felix Flex finds that pulleys on the exercise machines are not circular, but are cams--oval-shaped pulleys. At different orientations, the cams provide different ___.
Answerlengths of lever arms. forces required to produce a given torque.
Question:A metter stick is balanced at 50.0-cm mark. You tie a 10.0-N weight at the 15.0-cm mark. Where should a 30.0-N weight be place so that the meter stick will again be balanced?
Answer61.7-cm mark
Question:A 3-kg ball is whirled on the end of a string that is 2-m long. The ball's linear speed is 4-m/s. What is its angular momentum?
Answer:(24kg)(m)(m/s)
Question: 6A ring, a disk, and a solid ball having equal masses roll down a hill at teh same time. Which reaches the bottom first?
Answerthe ball.
Question:In physics, work is defined as...
Answer:force times distance.
Question:If you lift two loads up one story, how much work do you do compared to lifting just one load up one story?
Answer:twice as much.
Question:Power is defined as the...
Answer:work done on an object divided by the time taken to do the work.
Question:Potential energy is the energy an object has because of its...
Answer:location.
Question:The amount of potential energy possessed by an elevated object is equal to...
Answer:the work done in lifting it.
Question:An arrow in a bow has 70-J of potential energy. Assuming no loss of energy to heat, how much kinetic energy will it have after it has been shot...
Answer:70-J.
Question:When a car's speed tripples, its kinetic energy..
Answer:increases by nine times.
Question:A job is done slowly, and an identical job is one quickly. Both jobs require the same amount of work but different amounts of...
Answer:power.
Question:Which requires more work: lifting a 70-kg sack vertically 2 meters or lifting a 35-kg sack vertically 4 meters?
Answer:Both require the same amount of work.
Question:A ball is thrown into the air with 100-J of kinetic energy, which is transformed to gravitational potential energy at the top of its trajectory. When it returns to its original level after encountering air resistance, its kinetic energy is...
Answer:less than 100-J.
Question:An object that has kinetic energy mush be...
Answer:moving.
Question:An object that has kinetic energy mush have...
momentum.
Question:Which has greater kinetic energy, a car traveling at 30 km/h or a half-as-massive car traveling at 60 km/h?
Answer:The 60 km/h car.
Question:An object at rest may have...
Answer:energy.
Question:All simple machines ideally work on the principle that...
Answer:work input equals work output.
Question:The ratio of output force to input force of a simple machine is called the...
Answer:mechanical advantage.
Question:A pulley system can...
Answer:Change teh direction of a force, Multiply the force.
Question:The ratio of useful work output to total work input is called the...
efficiency.
Flashcard 1
Question: The force that accelerates a rocket into outer space is exerted on the rocket by what?
Answer: The exhaust gases.
Flashcard 2
Question: A 4-kg ball is thrown at 9 m/s. What is the ball's momentum?
Answer: 36 kg·m/s.
Momentum = mass × velocity = 4 kg × 9 m/s.
Flashcard 3
Question: A karate expert executes a swift blow and splits a cement block with her bare hand. What can be said about the forces, times, and impulses?
Answer: The forces on both the block and the expert's hand have the same magnitude, the times of impact are the same, and the impulses are the same.
Flashcard 4
Question: A freight train rolls along a track with considerable momentum. If it were to roll at the same speed but had twice as much mass, what would happen to its momentum?
Answer: Its momentum would be doubled.
Flashcard 5
Question: Which of the following has the largest momentum: a pickup truck traveling down the highway, a tightrope walker, a parked truck, a building, or a running dog?
Answer: A pickup truck traveling down the highway.
Momentum depends on both mass and velocity.
Flashcard 6
Question: Can the heavyweight champion of the world exert a force of 190 N on a piece of tissue paper held in midair with his best punch?
Answer: No, it cannot be done.
Flashcard 1
Question: A large truck and a small car traveling at the same speed have a head-on collision. Which vehicle undergoes the greater change in velocity?
Answer: The small car.
Flashcard 2
Question: A player catches a ball. Consider the action force to be the impact of the ball against the player's glove. What is the reaction to this force?
Answer: The force the glove exerts on the ball.
Flashcard 3
Question: When you jump off a step, you usually bend your knees as you reach the ground. By doing this, the time of impact is about 10 times more than it would be in a stiff-legged landing. How much is the average force on your body reduced?
Answer: About 10 times.
Flashcard 4
Question: An unfortunate bug splatters against the windshield of a moving car. Compared to the force of the car on the bug, what is the force of the bug on the car?
Answer: The same.
Flashcard 5
Question: A force is exerted on the tires of a car to accelerate the car along the road. The force is exerted by what?
Answer: The road.
Flashcard 6
Question: A moving freight car runs into an identical car at rest on the track. The cars couple together. Compared to the velocity of the first car before the collision, what is the velocity of the combined cars after the collision?
Answer: One half as large.
Flashcard 7
Question: Two people pull on a rope in a tug-of-war. Each pulls with 300 N of force. What is the tension in the rope?
Answer: 300
Flashcard 1
Question: In order to catch a ball, a baseball player moves his or her hand backward in the direction of the ball's motion. Doing this reduces the force of impact on the player's hand principally because of what?
Answer: The time of impact is increased.
Flashcard 2
Question: A karate chop delivers a blow of 2000 N to a board that breaks. What is the force that acts on the hand during this feat?
Answer: 2000 N.
Flashcard 3
Question: Two gliders having the same mass and speed move toward each other on an air track and stick together. After the collision, what is the velocity of the gliders?
Answer: Zero.
Flashcard 4
Question: A cannon recoils from launching a cannonball. Why is the speed of the cannon's recoil small?
Answer: The cannon has far more mass than the cannonball.
Flashcard 5
Question: Compared to a sports car moving at 30 miles per hour, how much momentum does the same sports car moving at 60 miles per hour have?
Answer: Twice as much momentum.
Flashcard 6
Question: Bronco the skydiver falls toward Earth. The attraction of Earth on Bronco pulls him down. What is the reaction to this force?
Answer: Bronco pulling up on Earth.
Flashcard 7
Question: An unfortunate bug splatters against the windshield of a moving car. Compared to the deceleration of the car, what is the deceleration of the bug?
Answer: Larger.
Flashcard 1
Question: Momentum of a system is conserved only when what?
Answer: There is no net external force acting on the system.
Flashcard 2
Question: Nellie Newton holds an apple in her hand. If the action is Earth pulling on the apple, what is the reaction?
Answer: The pull of the apple's mass on Earth.
Flashcard 3
Question: As a ball falls, the action force is the pull of Earth's mass on the ball. What is the reaction to this force?
Answer: The pull of the ball's mass on Earth.
Flashcard 4
Question: In order to increase the final momentum of a golf ball, what could we do?
Answer: All of the above (follow through when hitting the ball, increase the force acting on it, swing as hard as possible, increase the time of contact with the ball).
Flashcard 1
Question: The force required to maintain an object at a constant speed in free space is equal to what?
Answer: Zero.
Flashcard 2
Question: One object has twice as much mass as another object. What else does the first object have twice as much of?
Answer: Inertia.
Flashcard 3
Question: What is the minimum resultant possible when adding a 2-N force to a 10-N force?
Answer: 8 N.
Flashcard 4
Question: The weight of a person can be represented by a vector that acts in what direction?
Answer: Straight down, even if the person is standing on a hill.
Flashcard 5
Question: The mass of a dog that weighs 70 N is about how much?
Answer: 7 kg.
Flashcard 6
Question: A bag of groceries has a mass of 10.0 kilograms. What is its weight?
Answer: 98 N.
Question: Which has more mass, a kilogram of feathers or a kilogram of iron?
Answer: Neither—they both have the same mass.
Flashcard 2
Question: If the force of gravity suddenly stopped acting on the planets, what would they do?
Answer: They would move in straight lines tangent to their orbits.
Flashcard 3
Question: What would be the safest way to put up a clothesline?
Answer: With some slack in the line.
Flashcard 4
Question: A gymnast whose weight is 600 N hangs from the middle of a bar supported by two vertical strands. What is the tension in each strand?
Answer: 300 N.
Flashcard 5
Question: A clothesline is stretched between two trees. A tire hangs in the middle of the line, and the two halves of the line make equal angles with the horizontal. What is the tension in the line?
Answer: It is more than half the tire's weight.
Flashcard 6
Question: A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly. Why can this be done?
Answer: The milk carton has inertia.
Flashcard 7
Question: Friction is a force that always acts in which direction?
Answer: Opposite to an object's motion.
Flashcard 8
Question: An object following a straight-line path at constant speed:
Answer: Has zero acceleration
Flashcard 1
Question: After a cannonball is fired into frictionless space, the amount of force needed to keep it going equals what?
Answer: Zero, since no force is necessary to keep it moving.
Flashcard 2
Question: A 10-N force and a 40-N force act on an object in opposite directions. What is the net force on the object?
Answer: 30 N.
Flashcard 3
Question: The law of inertia states that an object does what?
Answer: Will continue moving at the same velocity unless an outside force acts on it.
Flashcard 4
Question: How much does a 4.0-kg bag of tools weigh?
Answer: 39.2 N.
Explanation: Weight = mass × gravity = 4.0 kg × 9.8 m/s².
Flashcard 5
Question: The law of inertia applies to what?
Answer: Both moving and nonmoving objects.
Flashcard 6
Question: A 7-N force and a 20-N force act in the same direction on an object. What is the net force on the object?
Answer: 27 N.
Flashcard 7
Question: Equilibrium occurs when what?
Answer: All of the above (the sum of the upward forces equals the sum of the downward forces, all the forces acting on an object are balanced, the net force on the object is zero, the sum of the x forces on an object equals the sum of the -x forces)
Flashcard 1
Question: An object weighs 10 N on Earth. A second object weighs 16 N on the moon. Which has the greater mass?
Answer: They have the same mass.
Flashcard 2
Question: Compared to its weight on Earth, a 10-kg object on the moon will weigh what?
Answer: Less.
Flashcard 3
Question: Compared to its mass on Earth, the mass of a 10-kg object on the moon is what?
Answer: The same.