Forces

FORCES
by Mr. Mike Gregory

Force

What is a Force

A Force is an action on an object that can change its shape, size and or velocity.

Simply put it is a PUSH or a PULL that can change the velocity of an object.

As you know from Newtons second law of motion, Force = Mass x Acceleration
giving Force the unit as Kg m/s² or Newton (N)

The Weakest force?

Gravity is a Force as well. Specifically, it is the Earth's Gravitational Force.

Gravitational force is the force of attraction that acts between all matter in the universe.

The acceleration due to gravity (how fast the earth pulls us) is 9.8m/s² which is approx 10m/s² .
In order for you to be able to stand up against the gravitational pull of the Earth, you have to push against it.

Suppose you weigh, 66 Kg, then to fights against gravity you must exert an equal or greater force than the earth. Force = Mass x Acc
= 66 x 10
Force = 660 N

Types of Forces

Magnetic

Forces in relation to motion or movement is called Mechanical force.

Eg: spinning motor, opening a door, swings.

Note: Muscular force is the raw force that humans/ animals use to move or do things.

Mechanical

The attractive or repulsive force exhibited my magnets is called Magnetic force.

Eg: Magnets ¯\_(ツ)_/¯

This is the attractive or repulsive force exhibited by electrically charged particles.

Eg: Hair clinging to statically charged ruler.

The force which acts parallel to the motion of an object and opposes the force acting upon it.

Eg: Being able to walk.
If it weren't for the opposing friction, you would slip every time you walk.

Electrostatic

Frictional

Friction exists in all states of motion. Even when in rest.

The friction experienced by a object in rest is called Static Friction.
An Object that is sliding experiences Sliding Friction.
And those objects which can roll experience Rolling Friction.

Fluid friction refers to the friction from fluids like air and water. You will learn more in higher classes.
Eg: Air Resistance.

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Types of Friction

Multiple Choice

What Force is acting here?

• Frictional Force

• Magnetic Force

• Electrostatic Force

• Anti-Gravitational Force