Force and Newton's Laws Test

Question 1

State the law of universal gravitation.

Answer 1

The force of gravity acts between all objects in the universe.

Question 2

What is weight?

Answer 2

Weight is the measure of the force of gravity on an object.

Question 3

Why do scientists prefer to describe matter by its mass instead of its weight?

Answer 3

Weight can change with location but mass will stay constant. Mass is how much matter is in an object.

Question 4

What are two factors that affect the strength of gravity?

Answer 4

Mass and distance

Question 5

How does mass and distance affect the gravitational attraction between two objects?

Answer 5

The more mass an object has, the greater the strength of its gravitational force; the greater the distance between two objects, the weaker the gravitational forces between them.

Question 6

List two things that contrasts balanced gravity against unbalanced gravity.

Answer 6

Net force equals zero, does not chance an object’s motion

Question 7

List two things that contrasts unbalanced gravity against balanced gravity.

Answer 7

Net force does not equal zero, changes an object’s motion

Question 8

Compare unbalanced and balanced gravity.

Answer 8

A push or pull, strength and direction

Question 9

What is static friction? Give an example.

Answer 9

Static friction is the friction that acts on objects that are not moving. Because of static friction, you must use an unbalanced force to start the motion of a stationary object.

Example – trying to move a stalled car to the side of the road. The heavier the object, the more static friction it has.

Question 10

What is sliding friction? Give an example.

Answer 10

Sliding friction occurs when two solid surfaces slide over each other. Sliding friction is caused by the microscopic roughness of all objects.

Example – throwing sand on an icy patch on the ground to help your footing

Question 11

What is fluid friction? Give an example.

Answer 11

Fluid friction occurs when a solid object moves through a fluid (gas or liquid). This friction is much easier to overcome than sliding friction. Lubricants are used to help reduce sliding friction.

Example – water on a water slide, applying oil to a squeaky gate hinge

Question 12

What is rolling friction?

Answer 12

Occurs when an object rolls across a surface. This friction is much easier to overcome than sliding friction. Rolling friction reduces the amount of contact between surfaces because of curved shape of a sphere/circle/

Example – wheels, ball bearings

Question 13

How is a force described?

Answer 13

Strength and direction.

Question 14

What is net force?

Answer 14

A combination of all forces acting on an object.

Question 15

How can you find net force if two forces act in opposite directions?

Answer 15

You would subtract to find the net force.

Question 16

Define Newton’s first law of motion.

Answer 16

An object at rest will stay at rest and an object moving at a constant velocity (motion) will continue to move at a constant velocity (motion), unless acted upon by an unbalanced force. This law is also called the Law of Inertia.

Question 17

Define Newton’s second law of motion.

Answer 17

The acceleration of an object depends upon the object’s mass and the net force acting on the object.

acceleration = force/mass

Question 18

Define Newton’s third law of motion.

Answer 18

For every action there is an equal and opposite reaction.

Question 19

When an object speeds up, slows down, or changes direction, why is an unbalanced force involved?

Answer 19

If an unbalanced force was not involved then there would be no change in the object’s motion.

Question 20

What are the SI units for acceleration, force, and mass?

Answer 20

acceleration = m/s²
mass = kg
force = N

Question 21

What two factors affect the force of friction?

Answer 21

the types of surfaces involved

how hard the surfaces are pressed together

Question 22

Identify one product of friction?

Answer 22

Heat, wear and tear, slows objects down

Question 23

In what direction does friction act in regards to an object’s motion?

Answer 23

Friction acts opposite the direction of motion.

Question 24

Thinking of Newton’s second law of motion, what are two ways to increase the acceleration of an object?

Answer 24

Decrease the mass of the object

Increase the force acting on the object

Question 25

Define centripetal force.

Answer 25

Any force that causes an object to move in a circular path. A center seeking force.

Question 26

How does gravity affect objects that are moving horizontally?

Answer 26

Gravity pulls objects that are moving horizontally toward the center of the Earth in the same way it pulls a dropped object.

Question 27

Why can an object have a constant speed and still be accelerating.

Answer 27

The object could be changing directions.

Question 28

Define inertia.

Answer 28

The tendency of an object to resist a change in its motion.

Question 29

How is mass related to inertia? Give an example.

Answer 29

The greater the mass, the greater the inertia.
Example – An aquarium full of water versus an empty aquarium. The aquarium with water has more mass so it has more inertia. Therefore it is harder to move.

Question 30

How does Newton’s first law explain what happens to passengers when a car stops quickly?

Answer 30

When a car stops quickly a person’s body wants to continue forward in a straight line even though the car is stopped. This is the result of a body’s inertia. If a person doesn’t wear a seat belt their head could hit the dash board or the windshield.

Question 31

When a rocket is launched, are the forces acting on it balanced or unbalanced? How do you know?

Answer 31

When a rocket is launched, are the forces acting on it balanced or unbalanced? How do you know?