Physics Chapter 2 test 1

If you pull horizontally on a crate with a force of 200 N, it slides across the floor in dynamic equilibrium. How much friction is acting on the crate?

200 N

How does Newton's first law of motion relate to Galileo's concept of inertia? a.Newton refined Galileo's concept of inertia and made it his first law of motion. b.Newton replaced Galileo's concept of inertia with his three laws of motion. c.Newton expressed Galileo's concept of inertia with the inertia equation. d.Newton's first law of motion refuted Galileo's concept of inertia.

a.Newton refined Galileo's concept of inertia and made it his first law of motion.

A bowling ball at rest is in equilibrium. Is the ball in equilibrium when it moves at constant speed in a straight-line path? a.Yes, the bowling ball is in equilibrium because ΣF = 0. b.The bowling ball is not in equilibrium because the wood of the bowling alley exerts an upward force on the ball. c.The bowling ball is not in equilibrium because ΣF = -mg. d.The bowling ball is not in equilibrium because it is moving.

a.Yes, the bowling ball is in equilibrium because ΣF = 0.

Newton said that something was needed to change the motion of an object. A clear reading of his first law tells us that what is needed is ______. a.a non-zero net force b.a force c.a net force d.no force at all

a.a non-zero net force

If you toss a coin straight upward while in a train moving at constant velocity, the coin will land a.as if you were at rest. b.in front of you. c.in back of you.

a.as if you were at rest.

Monkey Mo hangs from the middle of a horizontal rope. Tension in the rope is greatest if the rope a.sags very little. b.sags or doesn't sag, for tension is the same in any case. c.sags a lot. d.none of the above

a.sags very little.

The net force on any object in equilibrium is a.zero. b.non-zero when motion is involved. c.equal to its weight. d.less than its weight.

a.zero.

State the equilibrium rule for forces in symbolic notation a.ΣF = 0 b.ΣF = net force c.ΣF = 2 mg d.ΣF = -mg

a.ΣF = 0

How much support force acts on a 200-N girl standing on a weighing scale? a.No support force unless she stands on the floor b.200 N c.Less than 200 N d.More than 200 N

b.200 N

What are the units for force? a.Force must first be measured in newtons, then converted to pounds. b.Force can be expressed in newtons or pounds. c.Force must be measured in pounds and then converted to newtons. d.Force must be measured in newtons; it can never be measured in pounds.

b.Force can be expressed in newtons or pounds.

What did Galileo discover about moving bodies and force in his experiments with inclined planes? a.Bodies rolling up an inclined plane sped up. b.In the absence of a retarding force, a body will keep moving at a constant speed in a straight line forever. c.Bodies rolling down a steep inclined plane starting at a given height rolled up a gently inclined plane to a higher height. d.Bodies rolling down an inclined plane slowed down.

b.In the absence of a retarding force, a body will keep moving at a constant speed in a straight line forever.

A bird sitting in a tree is traveling at 30 km/s relative to the faraway Sun. When the bird drops to the ground below, does it still move at 30 km/s, or does this speed become zero? a.It has a speed of 30 km/s relative to the ground and the Sun. b.It continues to move at 30km/s relative to the Sun, but it has a speed of 0 km/s relative to the ground. c.It has a speed of 30 km/s relative to the Sun and -30 km/s relative to Earth. d.It comes to rest relative to the Sun and the ground.

b.It continues to move at 30km/s relative to the Sun, but it has a speed of 0 km/s relative to the ground.

Which of Newton's laws does the equilibrium rule illustrate? a.Newton's third law b.Newton's first law c.Newton's law of gravity d.Newton's second law

b.Newton's first law

What relationship between the Sun and Earth did Copernicus formulate? a.The Earth was at rest with respect to the Sun. b.The Earth revolved in a circle about the Sun. c.The Sun revolved in a circle about the Earth. d.The Sun and the Earth revolve in circles around each other.

b.The Earth revolved in a circle about the Sun.

If you push on a crate with a horizontal force of 100 N and it slides at constant velocity, what is the magnitude and direction of the frictional force acting on the crate? a.The frictional force on the crate is zero newtons. b.The frictional force on the crate is 100 N opposite the direction of motion. c.The frictional force on the crate is 100 N in the same direction as the direction of motion. d.The frictional force has nothing to do with you pushing on the crate

b.The frictional force on the crate is 100 N opposite the direction of motion.

What is the net force on a cart that is pulled to the right with 100 pounds of force and to the left with 30 pounds of force? a.The net force is zero. b.The net force is 70 pounds to the right. c.The net force is 70 pounds to the left. d.The net force is 130 pounds.

b.The net force is 70 pounds to the right.

When Dr. Hewitt pulls the tablecloth, what happens to the items on the tablecloth? a.They move vertically upward. b.They tend to stay where they were. c.They move horizontally in the opposite direction from the tablecloth. d.They move horizontally in the same direction as the tablecloth.

b.They tend to stay where they were.

Stand next to a wall that travels at 30 km/s relative to the Sun. With your feet on the ground, you also travel at the same 30 km/s. Do you maintain this speed when your feet leave the ground? What concept supports your answer? a.When you jump, your velocity relative to the Sun changes to -30 km/s so that your velocity relative to the wall is zero, because the forces on you are in equilibrium. b.When you jump, you continue to move at 30 km/s due to your inertia. c.When you jump, your velocity relative to the Sun drops to zero due to inertia. d.When you jump, your velocity relative to the Sun goes to zero because the forces on you are in equilibrium.

b.When you jump, you continue to move at 30 km/s due to your inertia.

Whirl a rock at the end of a string and it follows a circular path. If the string breaks, the tendency of the rock is to a.stop. b.follow a straight-line path. c.follow a circular path. d.slow down.

b.follow a straight-line path.

When Nellie Newton hangs by the ends of a rope draped over a large pulley, the tension in each supporting vertical strand is a.twice her weight. b.half her weight. c.equal to her weight. d.none of the above

b.half her weight.

The force that causes Earth to orbit the Sun is due to gravity, while the force needed to keep Earth moving as it circles the Sun is a.due to gravity. b.no force at all. c.due to both inertia and gravity. d.inertia.

b.no force at all.

A hockey puck sliding across the ice finally comes to rest because a.that's just the way it is. b.of friction. c.it seeks its proper and natural state.

b.of friction

When no forces act on moving objects their paths are normally a.ellipses. b.straight lines. c.circles. d.all of the above

b.straight lines.

While you are standing in the aisle of a bus, the driver suddenly makes a left turn. You lurch to the right due to a.an equilibrium challenge. b.your tendency to keep moving forward. c.an unbalanced force.

b.your tendency to keep moving forward.

What is the net force when a pair of 5-N forces simultaneously act in the same direction on an object? a.7.5 N b.5 N c.10 N d.0 N

c.10 N

The resultant of a 40-N force at right angles to a 30-N force is a.40 N. b.30 N. c.greater than 50 N. c.50 N.

c.50 N.

What did Galileo discover in his legendary experiment on the Leaning Tower of Pisa? a.Galileo found that stones fall faster proportional to their weight. b.Galileo found that air resistance significantly slowed falling stones. c.Galileo found that a heavier stone does not fall significantly faster than a lighter one. d.Galileo found that a heavier stone falls significantly faster than a lighter one.

c.Galileo found that a heavier stone does not fall significantly faster than a lighter one.

Dr. Hewitt has clay "blobs" hanging on either side of his head in this video. When he turns around, what happens to the blobs? a.The blobs fall off Dr. Hewitt's head. b.The blobs turn around in the opposite direction from Dr. Hewitt. c.The blobs tend to stay where they were. d.The blobs turn around in the same direction as Dr. Hewitt.

c.The blobs tend to stay where they were.

What concept was not understood in the 16th century when people couldn't conceive of a moving Earth? a.They did not understand relativity. b.They did not understand the parallelogram law of force addition. c.They did not understand inertia. d.They did not understand net force.

c.They did not understand inertia.

Some alphabet letters are floating in a bowl of soup. You want to move a letter that is far away from you closer to you. How could you rotate the bowl to do that? a.Rotate the bowl counterclockwise. b.Rotate the bowl clockwise. c.Unfortunately, neither rotating the bowl clockwise nor rotating it counterclockwise will work. d.Rotate the bowl either clockwise or counterclockwise, depending on where the letter is located.

c.Unfortunately, neither rotating the bowl clockwise nor rotating it counterclockwise will work.

The amount of force needed to sustain motion of a rock in outer space is a.a force less than its weight if friction is absent. b.a force equal to its weight. c.none of these

c.none of these

Inertia is defined as a a.force. b.change in motion. c.property of matter. d.none of the above

c.property of matter.

Earth continually moves about 30 km/s through space, which means the wall you stand next to also is moving at 30 km/s. When you jump vertically the wall doesn't slam into you because a.the speeds of you and Earth cancel out. b.your upward motion is small compared with Earth's speed. c.you're moving horizontally just as fast as the wall. d.motion of the Sun counteracts your motion.

c.you're moving horizontally just as fast as the wall.

Consider a book that weighs 15 N at rest on a flat table. How many newtons of support force does the table exert on the book? a.30 newtons up b.15 newtons down c.0 newtons d.15 newtons up

d.15 newtons up

Why do we say that force is a vector quantity? a.A force is measured in pounds, and pounds are a vector quantity. b.A force has a magnitude, but not a direction. c.A force is a scalar quantity. d.A force has a magnitude and a direction.

d.A force has a magnitude and a direction.

What does it mean to say something is in mechanical equilibrium? a.An object in mechanical equilibrium is always in motion. b.An object in mechanical equilibrium experiences a net force twice its weight. c.An object in mechanical equilibrium must experience no forces. d.An object in mechanical equilibrium experiences a zero net force.

d.An object in mechanical equilibrium experiences a zero net force.

When Dr. Hewitt pulls the tablecloth, why do the items on the tablecloth do what they do? a.Friction with the tablecloth is keeping them there. b.They are attached to the tablecloth. c.Friction with the table is keeping them there. d.Inertia makes them stay at rest.

d.Inertia makes them stay at rest.

What type of path does a moving object follow in the absence of a force? a.It moves in a straight line and eventually slows to a stop. b.It follows a circular path in the absence of a force. c.It follows a parabolic trajectory in the absence of a force. d.It continues to move in a straight line at a constant speed.

d.It continues to move in a straight line at a constant speed.

What two classes of motion did Aristotle advocate? a.Earthly motion and heavenly motion b.Propelled motion and passive motion c.Vertical motion and horizontal motion d.Natural motion and violent motion

d.Natural motion and violent motion

What did Copernicus say about the motion of the Sun? a.The Sun circles Earth each 24 hours. b.The Sun circles Earth each 365 days. c.The Sun rises and falls each 24 hours. d.The Sun is stationary and Earth circles it.

d.The Sun is stationary and Earth circles it.

According to the parallelogram rule, what quantity is represented by the diagonal of a constructed parallelogram? a.The diagonal is 1.41 times the magnitude of the longest vector. b.The diagonal is the difference of two vectors. c.The diagonal is always 1.41 times the magnitude of the sum of the vectors. d.The diagonal is the resultant, or sum, of two vectors

d.The diagonal is the resultant, or sum, of two vectors

What is the net force on a bag pulled down by gravity with a force of 18 newtons and pulled upward by a rope with a force of 18 newtons? a.The net force is 18 newtons. b.The net force is 36 newtons. c.The net force is 25 newtons. d.The net force is zero newtons.

d.The net force is zero newtons.

What is the net force on an object in either static or dynamic equilibrium? a.The net force is vertical for static equilibrium and horizontal for dynamic equilibrium. b.The net force is equal and opposite to the weight of the object. c.The net force is zero for static equilibrium and greater than zero for dynamic equilibrium. d.The net force is zero.

d.The net force is zero.

What is the resultant of a pair of one pound forces at right angles to each other? a.The resultant is a force of 2.0 pounds in a direction bisecting the angle between the two vectors. b.The resultant is zero force. c.The resultant is a force of 1.0 pound in a direction bisecting the angle between the two vectors. d.The resultant is a force of 1.41 pounds in a direction bisecting the 90-degree angle between the two vectors.

d.The resultant is a force of 1.41 pounds in a direction bisecting the 90-degree angle between the two vectors.

Why do the alphabet letters tend to do what they do when you rotate the bowl? a.The soup prevents the letters from moving. b.The sides of the soup bowl prevent the letters from moving. c.The letters are heavier than the soup, so they cannot move even though the soup moves. d.They have inertia−the tendency of an object at rest to stay at rest.

d.They have inertia−the tendency of an object at rest to stay at rest

Why do the clay blobs do what they do when Dr. Hewitt turns around a.Friction with the head is keeping them there. b.Dr. Hewitt is holding them there. c.Dr. Hewitt is turning them back to their original position. d.They have inertia−the tendency of an object at rest to stay at rest.

d.They have inertia−the tendency of an object at rest to stay at rest.

You tell your friend about the neat tablecloth trick that Dr. Hewitt demonstrated. Your friend tries to repeat this trick at home and later complains to you that it failed. Which of the following is most likely the reason that it failed? a.Your friend is too clumsy. b.The items placed on the tablecloth were too light. c.Your friend pulled the tablecloth too quickly. d.Your friend pulled the tablecloth too slowly.

d.Your friend pulled the tablecloth too slowly.

When you stand at rest on a bathroom scale, how does your weight compare with the support force from the scale? a.Your weight is equal in magnitude and in the same direction as the support force from the scale. b.The support force from the scale is twice your weight. c.The support force from the scale is half your weight. d.Your weight is equal in magnitude and opposite in direction to the support force from the scale.

d.Your weight is equal in magnitude and opposite in direction to the support force from the scale.

An object in mechanical equilibrium is an object a.moving with constant velocity. b.having no changes in velocity. c.at rest. d.all of the above

d.all of the above

When you flick a card from beneath a coin that hardly moves, you're illustrating a.friction. b.support force. c.equilibrium. d.inertia.

d.inertia.

Galileo taught us that if you roll a ball along a level surface it will a.soon slow down due to its natural place. b.roll as long as its inertia nudges it along. c.soon roll in the opposite direction. d.keep rolling if friction is absent.

d.keep rolling if friction is absent.

A hockey puck is set in motion across a frozen pond. If ice friction and air resistance are neglected, the force required to keep the puck sliding at constant velocity is a.equal to its weight. b..equal to its mass times its weight. c.equal to its weight divided by its mass. d.none of the above

d.none of the above

A force of gravity pulls downward on a book on a table. What force prevents the book from accelerating downward? Enter the name of the force only

support