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Physics Chapter 3 Review

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Aristotle divided motion into two types: ___ and ___
natural motion and violent motion
Natural motion on Earth was once thought to be either ___ or ___.
straight up or straight down
Aristotle thought that it was natural for heavy things to ___ and for light things to ___.
fall and rise
Aristotle also thought that ___ motion was natural for objects beyond Earth and that the planets and stars moved in perfect circles around ___.
circular; Earth
What force was thought to have caused a horse and cart to experience violent motion?
the pull of the horse
Before the 1500's, the proper state of objects was thought to be one of ___, unless they were being pushed or pulled or were moving toward their natural resting place.
rest
T/F: Early thinkers thought that violent motion was imposed motion.
true
T/F: It was commonly thought by many ancient thinkers that if an object moved "against its nature," then a force of some kind was responsible.
true
T/F: Copernicus thought that Earth and other planets move around the sun.
true
T/F: Copernicus thought that Earth was at the center of the universe.
false
T/F: Copernicus did not publish his ideas until he was near death.
true
T/F: Copernicus lived a long and happy life after his works were published.
false
Why did Copernicus do most of his work in secret?
Copernicus' ideas were very controversial, so he worked in secret to avoid persecution.
What was one of Galileo's great contributions to physics?
demolishing the notion that a force is necessary to keep an object moving
A force is any ___ or ___.
push or pull
Explain what friction is and how it acts.
Friction is the force that acts between materials that touch as they move past each other. Friction is caused by irregularities in the surfaces that are touching. All irregularities obstruct motion causing a force (friction) that opposes motion.
When a slope is downward...
speed increases
When a slope is upward...
speed decreases
When there is no slope...
speed remains the same
Based on his experiments with rolling balls, Galileo was able to conclude that when friction is present, a ___ is needed to keep an object moving.
force
Describe the property of inertia in your own words.
A body in motion will stay in motion unless acted on by a force. Likewise, a body at rest will stay at rest unless acted on by a force. Or, every object resists change to its state of motion.
What is another name for Newton's first law of motion?
the law of inertia
State Newton's first law of motion.
Newton's first law states that every object continues in a state of rest, or of uniform speed in a straight line, unless it is acted on by a nonzero net force.
Use Newton's first law of motion to explain what happens to dishes on a table when the tablecloth is quickly pulled from beneath them.
Dishes on a tabletop are at rest. They tend to remain at rest even when the tablecloth is not significant enough to move the dishes very much.
Objects in a state of rest tend to remain at rest; only a ___ will change that state.
force
Use Newton's first law of motion to explain why and air hockey puck slides on the game table with no apparent loss in speed. Name two things that can cause the puck to change its state of motion.
In the absence of forces, a moving object such as the air hockey puck will move indefinitely in a straight line. The puck will change its motion if it is struck or if it hits the side of the playing table.
Once an object is moving in a force-free environment, for how long will it move in a straight line?
indefinitely
T/F: The amount of inertia an object has depends on its mass.
true
T/F: The more mass an object has, the greater its inertia.
true
T/F: Volume and mass are the same quantity.
false
T/F: Mass is usually measured in kilograms.
true
Does a pillow or a battery have more mass? volume? inertia?
The battery has greater mass and thus greater inertia. The pillow has greater volume.
T/F: Mass is a measure of the gravitational force acting on an object.
false
___ is a measure of the amount of material in an object and depends on the number of and kind of atoms that compose it.
mass
T/F: A stone has the same mass on Earth and on the moon, but its weight is less on the moon.
true
___ is the quantity of matter in an object.
mass
___ is the force of gravity on an object.
weight
traditional unit of weight in the United States
pound
measure of matter in most parts of the world
mass
SI unit of mass
kilogram
SI unit of force
newton
If Earth is rotating at 30 km/s, explain how a bird sitting on a tree can drop down vertically and grab a worm that is crawling on the ground.
Earth, the bird, the tree, the ground, and the worm are all rotating as one unit. Because everything is rotating as one unit, Earth's rotation does not affect the bird's ability to descend vertically to grab the worm.
A girl is sitting on a bus that is traveling at 30 km/h. She is throwing her tennis ball gently into the air and catching it. T/F The tennis ball is moving faster than the girl riding the bus.
false
A girl is sitting on a bus that is traveling at 30 km/h. She is throwing her tennis ball gently into the air and catching it. T/F The tennis ball is behaving as if the bus were at rest.
true
A girl is sitting on a bus that is traveling at 30 km/h. She is throwing her tennis ball gently into the air and catching it. T/F The inertia of the tennis ball changes when it is thrown.
false
A girl is sitting on a bus that is traveling at 30 km/h. She is throwing her tennis ball gently into the air and catching it. T/F Gravity affects only the vertical motion of the tennis ball.
true
did not recognize inertia
Aristotle
developed the law of inertia
Newton
believed that horizontal motion was "unnatural"
Aristotle
was one of the first to recognize that no force was needed to keep an object in motion
Galileo
T/F: In the fourth century B.C., Aristotle divided motion into two types: natural motion and violent motion.
true
The law of inertia states that an object

a. will continue moving at the same velocity unless an outside force acts on it.
b. will continue moving in a straight line unless an outside force acts on it.
c. that is not moving will never move unless a force acts on it.This answer is incorrect.
d. at rest will remain at rest unless acted on by an outside force.
e. will do all of the above.
will do all of the above
The property of a body to resist changes to its state of motion is called ___ .
Inertia
Friction is caused by the ___ in the surfaces of objects that are touching.
irregularities
Galileo found that a ball rolling down one inclined plane would roll how far up another inclined plane?

a. To nearly half its original height
b. To about one quarter its original height
c. The ball would not roll up the other plane at all.
d. To nearly its original height
e. To nearly twice its original height
d. To nearly its original height
Compared to its mass on Earth, the mass of a 10-kg object on the moon is

a. more.
b. the same.
c. less.
b. the same.
T/F: The SI unit of force is the kilogram.
false
The SI unit of force is the ___ .
Newton
Compared to its weight on Earth, a 10-kg object on the moon will weigh

a. more.
b. the same amount.
c. less.
less
T/F: The amount of matter in an object is its weight.
false
Friction is a force that always acts

a. opposite to an object's motion.
b. in the same direction as an object's motion.
c. perpendicular to an object's motion.
a. opposite to an object's motion.
The force required to maintain an object at a constant speed in free space is equal to

a. the mass of the object.
b. the weight of the object.
c. zero.
d. the force required to stop it.
e. none of the above
c. zero.
The law of inertia applies to

a. objects at rest.
b. moving objects.
c. both moving and nonmoving objects.
c. both moving and nonmoving objects.
The property of a body to resist changes to its state of motion is called ___ .
Inertia
T/F: The SI unit of mass is the newton.
false
___ is the force of gravity on an object.
Mass
Which has more mass, a kilogram of feathers or a kilogram of iron?

a. The feathers
b. Neither—they both have the same mass.
c. The iron
b. Neither—they both have the same mass.
A 15-N force and a 45-N force act on an object in opposite directions. What is the net force on the object?
30N (but the answer on the quiz said 60N)
What is the maximum resultant possible when adding a 2-N force to an 8-N force?
10N
A 5-N force and a 30-N force act in the same direction on an object. What is the net force on the object?
35N
What is the minimum resultant possible when adding a 5-N force to an 8-N force?
3N
Equilibrium occurs when:
all the forces acting on an object are balanced
the sum of the +x forces on an object equals the sum of the -x forces
the net force on the object is zero
the sum of the upward forces equals the sum of the downward forces
all of the above
all of the above
a girl whose weight is 500N hands from the middle of a bar supported by two vertical strands of rope. What is the tension in each strand?
250N
The astronomer Copernicus publicly stated in the 1500s that Earth
revolves around the sun
Galileo found that a ball rolling down one inclined plane would roll how far up another inclined plane?
to nearly its original height
The law of inertia states that an object:
will continue moving at the same velocity unless an outside force acts on it.
will continue moving in a straight line unless an outside force acts on it.
that is not moving will never move unless a force acts on it
at rest will remain at rest unless acted on by an outside force
will do all of the above
will do all of the above
The law of inertia applies to
both moving and nonmoving objects.
After a cannonball is fired into frictionless space, the amount of force needed to keep it going equals
zero, since no force is necessary to keep it moving
A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly. The reason this can be done is that
the milk carton has inertia
One object has twice as much mass as another object. The first object has twice as much
inertia
Which has more mass, a kilogram of feathers or a kilogram of iron?
neither - they both have the same mass
Which of the following is NOT true about Aristotle's concept of violent motion?
Violent motion is imposed motion.
Violent motion has an external cause.
Violent motion is the result of forces that push or pull.
Violent motion is thought to be either straight up or straight down.
Violent motion is thought to be either straight up or straight down.
You and a friend are jumping on a trampoline. Why does Earth, which is rapidly orbiting around the sun, not move under your feet when you jump?
Newton's first law holds that your body moves along with Earth because it is not compelled to change its motion by an unbalanced force.
T/F: Friction refers to the force between two surfaces that are sliding past each other.
true
T/F: A force can be simply defined as a push or a pull.
true
T/F: The reason a penny thrown straight up inside an airplane will come back to your hand is that you, the air inside the plane, and the penny are all moving at the same horizontal velocity.
true