Force, levers, centre of gravity

Question 1

Unit of force

Answer 1

Newton (N)

Question 2

How to measure force

Answer 2

Can be measured using a spring balance (A newton meter)

Question 3

Types of forces

Answer 3

Gravity
Magnetic
Electric
Friction

Question 4

What is friction?

Answer 4

A force that opposes motion between two objects in contact.

Question 5

When can friction be a nuisance?

Answer 5

It slows thongs down when you don’t want it to

eg. driving a car or riding a bike

Question 6

When can friction be useful?

Answer 6

Brakes on a bike

Enable us to walk

Question 7

What is a force?

Answer 7

A force is a push or pull. It causes a stationary object to move.

Question 8

How to measure weight

Answer 8

Weight (Newtons) = Mass (kg) x 10

Question 9

Grams in kg

Answer 9

1000

Question 10

Hooke’s law

Answer 10

Hooke’s law states that the extension of an elastic body (a spring) is directly proportional to the force causing the extension.

Question 11

What does Hooke’s law mean?

Answer 11

If the force on a string douboes, so will the extension (length of string)

If force tripes, then extension will also triple, etc.

Question 12

how to calculate the moment of a force

Answer 12

force x distance (perpendicular distance from fulcrum to the line of
action of the force)

Question 13

everyday applications of levers

Answer 13

scissors
door
wheelbarrow
seesaw

Question 14

law of the lever

Answer 14

When a lever is balanced the sum of the clockwise moments equals the sum of the anticlockwise moments.

Question 15

What is the centre of gravity?

Answer 15

The centre of gravity is a point in the object which all the weight of the object appears to act.

Question 16

centre of gravity example

Answer 16

If you were to lean too far forward, you will fall flat on your face.

Coke can experiment

Question 17

lever

Answer 17

a rigid body that can turn about a fixed point called a fulcrum