Physics Chapter 3 Test

What did Galileo find about a ball?

A ball rolling on a smooth horizontal plane has almost constant velocity, and if friction were entirely absent, the ball would move forever. He stated that the tendency of a body to keep moving is natural and that every object resists change to its state of motion.

What was the proper state of objects thought to be?

A state of rest, unless they were being pushed or pulled or were moving toward their natural resting place.

Which foremost Greek Scientist studied motion?

Aristotle; He divided it into two types: natural motion and violent motion

What was Copernicus' reasoning?

Copernicus reasoned that the simplest way to interpret astronomical observations was to assume that Earth and the other planets move around the sun.

What did Newton say about forces?

Forces are needed to overcome any friction that may be present. Forces are also needed to set objects in motion initially. Once an object is moving in a force-free environment, it will move in a straight line indefinitely.

What did Galileo argue?

Galileo argued that only when friction is present-as it usually is- is a force needed to keep and object moving. One of his greatest contributions was demolishing the fact that a force (a push or pull) is necessary to keep an object moving.

What was controversial about Copernicus' ideas?

His idea of motion in space was controversial at the time because most people believed that Earth was the center of the universe. Copernicus worked on his ideas in secret to escape persecution. He published his ideas at the urging of his friends.

How is matter measured in most parts of the world?

In units of mass. SI unit of mass=kilogram (kg)

What is the relationship between weight and mass?

Mass and weight are proportional to each other in a given place. Objects with greater mass have greater weight; Objects w/ little mass have little weight

What was natural motion?

Natural Motion on Earth was thought to be either straight up or straight down: It was "natural" for heavy things to fall and for very light things to rise.

Other information

Notions of today are very different from those of our distant ancestors (Aristotle...)

What does the law of inertia state (simple terms)?

Objects in motion remain in motion if no unbalanced forces act on them.

What did Newton's work show about Earth?

Objects on Earth move with Earth as Earth moves around the sun. (The law of inertia also shows that objects within moving vehicles move with the vehicles)

What does Newton's First Law State/ another name for it?

The Law of Inertia; Every object continues in a state of rest, or of uniform speed in a straight line, unless acted on by a nonzero net force.(This idea replaced Aristotelian ideas)

What is weight?

The force of gravity on an object that depends on the object's location. (different from mass, which is the same on Earth, moon, and in outer space.)

Relationship between mass and inertia

The more mass an object has, the greater its inertia and the more force it takes to change its state of motion.

What is mass?

The quantity of matter in an object; the measure of inertia of an object; measured in kilograms (kg)

Copernicus announced the idea of...

a moving Earth in the 16th century. This was controversial and stimulated much argument/debate

The law of Inertia applies to a. objects at rest b. moving objects c. both moving and non moving objects

c. both moving and non moving objects

If the force of gravity suddenly stopped acting on the planets, they would a. spiral slowly toward the sun b. continue to orbit the sun c. move in straight lines tangent to their orbits d. spiral slowly away from the sun e. fly straight away from the sun

c. move in straight lines tangent to their orbits

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 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 d. at rest will remain at rest unless acted on by an outside force e. will do all of the above

e. will do all of the above

What was violent motion?

imposed motion and it was the result of forces that pushed or pulled

What is friction?

the force that acts between materials that touch as they move past each other.

What is the SI unit of force?

the newton (N) - capital N because it is named after person

What is inertia?

the property of a body to resist changes to its state of motion

True or False: 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