Forces and Motion

Essential Standard 1.2

Understand the relationship between

forces and motion.

Learning Objective 1.2.2

Classify frictional forces into one of four

types: static, sliding, rolling, and fluid.

I Can StatementsAt the end of this lesson, you should be

able to say, with confidence:

• I can explain the relationship between force

and motion

• I can distinguish between balanced and

unbalanced forces

• I can describe four types of frictional forces

A Force is a Push or Pull that One Object

Exerts on Another

Force

In order for there to be any motion, a force must

be applied.

The direction of the

motion will be in the

direction of the force

applied.

Force and Motion

In order to change the direction of the motion,

another force has to be applied.

Changing Motion

When two or more forces combine at the

same time, they create a net force.

Net Forces

Force Force Net Force

Balanced forces occur when the forces are

equal in size and opposite in direction

Balanced Forces

Force 1 Force 1 Force 1 Force 1

Net Force 2 Net Force 2

Force 1 Force 1 Force 1 Force 1

Net Force 2 Net Force 2

No MovementBecause balanced forces are equal in size and

opposite in direct, they cancel each other out, so

the net force is zero and no movement occurs.

Net Force = 2 – 2 = 0

Unbalanced forces are unequal in size and the

direction of the movement is determined by the

larger force.

Unbalanced Forces

Net Force 3 Net Force 2

Total Net Force = 3 - 2 = 1

Friction is the force that opposes motion between two surfaces that are touching

each other.

Friction

Even though friction opposes motion, without it we wouldn’t be able to walk or drive.

Friction

Static FrictionStatic Friction occurs between two objects that

are not moving.

In order to move an

object, you have to

apply enough force to

overcome the static

frictional force.

Static Friction is the hardest frictional force to

overcome.

Sliding Friction is the force that opposes the

motion of two surfaces sliding past each other.

Sliding friction is

easier to overcome

than static friction.

Sliding Friction

Isn’t it much easier to slide a heavy box than

carry it?

Rolling friction occurs between an object that is

rolling and the surface it is rolling upon.

Rolling Friction

Rolling friction is easiest frictional

force to overcome.

Fluid FrictionFluid friction occurs when a solid object moves

through a fluid.

Fluids are anything that flows, so both water

and air are fluids. (Air Resistance)

StreamliningStreamlined objects try to reduce fluid friction by

helping the fluid flow over the object.

ParachutesParachutes are designed to increase air

resistance to slow down movement by increasing

surface area.

The End