Balanced and Unbalanced Forces

Prepared By: SYAZA IZZATY ISMAIL

What is a force? A force is a push or a pull (measured in

newtons,N). Forces are represented by arrows (always in

pairs) which point the way the force is acting - the bigger the arrow, the bigger the force (balanced forces have equally sized arrows)

Balanced forces - stationary /

steady speed

Balanced forces - stationary / steady speed

Force

Forces come in pairs Forces have a magnitude and a

direction

5N, north (up) Magnitude: 5NDirection: north (up)

Balanced and Unbalanced Forces

Forces occur in pairs and they can be either balanced or unbalanced

Balanced Forces

Balanced forces do not cause change in motion

They are equal in size and opposite in direction

Unbalanced Forces An unbalanced force always causes a change in

motion

When unbalanced forces act in opposite directions you can find the net forceNet force:

Magnitude The difference between the two forces

Direction Direction of the largest force

Unbalanced Forces

3 N, right – 6 N, left = 3N, left

Unbalanced Forces

4 N, left – 10 N, right = 6N, right

Unbalanced Forces

5 N, right + 10 N, right =15N, right

EXAMPLE 1 In which of the pictures will the object move

- what direction and with what force?

1)The first has a balanced force: 2N – 2N = 0 (there is no movement)

2)The second has a force of: 4N - 1N = 3N (move to the right)

EXAMPLE 2 A hammer hits a nail with a downward force

of 50N - what is the size and direction of the force of the nail on the hammer?

Complete the sentences below using the keywords: downwards; equal; opposite; and upwards: -a. The force on a ladder resting against a

wall is an to the force of the wall on the ladder

b. A book is a rest on a table. The force of the book on the table is and the force of the table on the book is

equal

opposite

downwards

upwards

50N upwards

LET’S DO IT! When standing on some bathroom

scales they read 500N. i) What is the size and direction of the

force of the student on the scales? ii) What is the size and direction of the

force of the scales on the student? A lorry tows a broken-down car -

when the force of the lorry on the tow rope is 200N, what is the force of the tow rope on the lorry?

500N upwards

500N downwards

200N