Chapter 4- Newtons Laws

Question 1

What is a Force?

Answer 1

Any push or pull

Question 2

What do forces do to an object?

Answer 2

Forces may change the motion of an object. They may combine with other forces to affect
motion.

Question 3

Contrast Contact and Field Forces

Answer 3

Contact forces act between objects that are in contact with each other. The forces only act
when the objects are in contact. Ex: Friction, ordinary pushes and pulls.
Field forces act without contact. Ex: Gravity, Electromagnetism.

Question 4

What is Inertia?

Answer 4

Inertia is the tendency of an object to resist a
change in its motion.

Question 5

What is Mass?

Answer 5

Mass is a measure of the quantity of matter in an object, and of the Inertia of an object.

Question 6

Why is Mass important for force and acceleration?

Answer 6

mass resists acceleration

Question 7

What is Equilibrium?

Answer 7

The state at which the net forces acting on an object equal 0

Question 8

How to objects move when in equilibrium?

Answer 8

They move at a constant velocity, or don’t move at all

Question 9

How do objects move when there is a net force acting on them?

Answer 9

Objects accelerate in the direction of net force, in direct proportion to net force, and in inverse proportion
to mass.

Question 10

State Newton’s second law according to force, mass, and acceleration?

Answer 10

Acceleration is directly proportional to net force and inversely proportional to mass

Question 11

What is Friction?

Answer 11

Friction is a force that acts between surfaces in contact that resists motion between the objects.

Question 12

Contrast Kinetic and Static Friction

Answer 12

Static friction acts between surfaces that are not moving with respect to each other. It builds in response to applied
force and acts to resist the start of motion, up to a maximum amount.
Kinetic friction is a constant force that acts to resist the motion of objects in contact with each other that are
moving with respect to each other.

Question 13

What is weight?

Answer 13

Weight is the force of gravity acting on an object from the planet that it is on.

Question 14

How do we calculate weight

Answer 14

Fg=mg

Gravitational force = mass times gravity

Question 15

What do you multiply kg to get lbs

Answer 15

2.2

Question 16

Compare the weight of an object on the moon and earth

Answer 16

An object weighs less on the moon than on Earth because the moon has weaker gravity, due to its much smaller mass than Earth.

Question 17

Explain in terms of gravitational force and Newton’s 2nd Law why two objects of differing mass still experience the same acceleration due to gravity?

Answer 17

Fg=mg
a=Fnet/m
In free fall Fnet=Fg
A=mg/m
A=g

Question 18

What is Newtons law of universal gravitation?

Answer 18

All objects attract all other objects through gravity. That attraction is proportional to the masses of the objects, and inversely proportional to the square of the distance between them.

Question 19

What is momentum?

Answer 19

Momentum is: Mass in motion, Inertia in motion, but best described as a measure of how hard it is to stop a moving object. Momentum = mass x velocity.

Question 20

What is impulse?

Answer 20

Impulse is Force applied for some amount of time. Impulse = net force x time.

Question 21

How are impulse and momentum related?

Answer 21

Impulse equals change in momentum.

Question 22

What is the law of Conservation of Momentum?

Answer 22

The momentum of any closed system does not change.

Question 23

What is a closed system?

Answer 23

A closed system has no external forces acting on it that may change the momentum of the system, and there are no changes in mass within the system.

Question 24

How do airbags save lives?

Answer 24

Airbags reduce the force acting to change the momentum of your body by increasing the amount of time over which your momentum is changed.