Types of Interactions 1

4

The Transfer of Forces

Return to Table
of Contents

5

Let's review Newton's Laws of Motion.

With a partner, describe Newton's Three
Laws of Motion.

Record your answers on the next slide.

Forces in the Universe

6

Review: Newton's Laws

First Law:

Second Law:

Third Law:

An object in motion will stay in motion and an object
at rest will stay at rest, unless acted upon by an outside
(unbalanced) force

Acceleration depends on both force and mass. The
more mass the less acceleration, but the more force
the greater the acceleration.

For every action there is an equal and opposite reaction.

This is known as Action-Reaction Forces.

7

Work in your group to brainstorm some ways that
forces can be applied to an object.

Write them down on your notes and be prepared
to share your groups ideas.

What are some ways we can
apply a force to an object?

QUESTION
?

8

Some forces can be transferred by actually touching an object.

Other forces are able to work without touching an object, even through
empty space!

Forces Acting on Objects

9

Let's Classify the Forces into 2 Categories

Forces that act by Direct
Contact
(by touching)

Forces that Act without Direct Contact
(without touching)

friction

gravity

10

The forces that act over a distance are going to be exerted over what
we call a "field". These forces are called field forces.

Definition of field (from Physics):
A region of space characterized by a physical property, such as
gravitational or electromagnetic force or fluid pressure, having a
determinable value at every point in the region.

Forces Acting Over a Distance

Multiple Choice

Which of the following is NOT an

example of a force being exerted through a field?

• A man pushing a car

• A magnet pulling a metal object

• A gravitational force between two planets

• A wind pushing a kite

11

1

Which of the following is NOT an
example of a force being exerted through a field?

A
Gravity pulling on a falling apple

B

A man pushing a car

C

A magnet attracting a steel ball

D
An electrically charged balloon pushing on
another balloon from across the room

Answer

this is the only one that requires

touching (contact)

Multiple Choice

A balanced force acting on an object will cause it to accelerate (change velocity).

• False

• True

12

2

A balanced force acting on an object
will cause it to accelerate (change velocity).

True

False

Answer

balanced means it's in equilibrium and will

remain at rest (it won't move)

13

Force Acting Through Fields

Is the red ball affected by Earth?

What force is at work in this diagram?

Here's one example of a force
acting through a field over a
distance without touching .

14

Newton's Universal Law of Gravitation

A teacher can even exert a force of
gravitation on their students!

Click here to see a video on the Law of
Gravitation

Any two objects with mass will exert a force of attraction
to each other even over vast distances. This force acts on
both objects, pulling them towards each other.

Multiple Choice

What factors affect the force of gravity between two  objects? 

• Mass and distance of the objects

• Temperature of the objects

• Magnetic field of the objects

• Color of the objects

15

3 What factors affect the force of gravity between two
objects? (Choose all that apply.)

A mass of the objects

B weight of the objects

C distance between the objects

D force of the objects

Answer

gravity depends on mass and distance:

bigger mass = bigger gravity
closer distance = stronger gravity
and vice versa

Multiple Choice

What happens to the force of gravity between two objects as they move apart?

• Decreases due to distance

• Increases due to speed

• Becomes weaker over time

• Is unaffected by the objects' movement

16

4 What happens to the force of gravity between two
objects as they move apart?

A Increases due to distance

B Decreases due to distance

C Nothing because the masses dont change

D impossible to tell without knowing what the objects
are

Answer

closer = stronger

Multiple Choice

When talking about the gravity between you and Earth, Earth has a larger force acting on it than you do.

• False

• True

17

5 When talking about the gravity between you and Earth,
Earth has a larger force acting on it than you do.

True

False

Answer

no, it's always equal and opposite
we just happen to be a lot smaller so we
may not notice it as much