Moments

Question 1

What is the moment of a force?

Answer 1

A force which has a turning effect if it acts on an object fixed at a pivot

Question 2

A force will have a turning effect if…

Answer 2

It acts on an object fixed at a pivot

Question 3

Give two other words for ‘moment’ which mean the same thing

Answer 3

• turning effect

- torque

Question 4

How do you calculate the moment of a force?

Answer 4

The moment (m) of a force is given by:

M=FD
Where M = moment of the force (Nm)
F = size of the force (N)
D = perpendicular distance from the pivot to the line of action of the force (m)

Question 5

The moment of any force acting through the pivot is…

Answer 5

Zero

Question 6

What is the principle of moments?

Answer 6

If an object is in equilibrium, the total clockwise moment acting on it equals the total anti-clockwise moment acting on it

Question 7

When do we use the principle of moments?

Answer 7

We use the principle of moments when we are finding an unknown force or distance for a balanced lever

Question 8

How do practical levers help us do work more easily?

Answer 8

• practical levers help us do work more easily if the pivot is placed near one end instead of at the middle
• if the pivot is nearer to the load than the effort then the lever acts as a force magnifier

Question 9

What is a force magnifier?

Answer 9

Since the moment caused by the load exceeds the moment caused by the effort, if the effort is much farther from the pivot than the load is, then the effort can lift a load much larger than itself

Question 10

What is the formula we use for practical levers?

Answer 10

Effort x effort distance = load x load distance

Question 11

Why is a wheelbarrow a force magnifier?

Answer 11

A wheelbarrow is a force magnifier because the effort is applied much farther from the pivot than the load is