Chapter 34 - Force

Question 1

What is force?

Answer 1

Causes a stationary object to move

Question 2

What is force measured in?

Answer 2

Newtons (N)

Question 3

Describe gravity as a force

Answer 3

• The force that pulls objects towards the earth

- E.g a pen rolling off a table -> gravity pulls it towards the floor

Question 4

Describe magnetic force

Answer 4

• Magnetic force attracts and repels objects

- E.g a magnet will attract a metal paperclip

Question 5

Describe electric force

Answer 5

• E.g when you rub a plastic pen on the sleeve of your jumper, you can pick up tiny pieces of paper
• The pen has become electrically charged and the electric force attracts the pieces of paper

Question 6

What is friction?

Answer 6

A force that opposes the sliding motion of an object when in contact with another object

Question 7

What are two advantages of friction?

Answer 7

• Friction allows us to walk, without it we would slip

- The friction between the brake pad and the wheel causes the bike to stop

Question 8

What are two disadvantages of friction?

Answer 8

• Friction causes the wearing of moving surfaces in contact

- Friction can give you blisters -> new shoes

Question 9

Lubrication

Answer 9

Used to reduce the friction between two surfaces in contact

-E.g Joints in the human body are surrounded by a fluid that acts as a lubricant

Question 10

Describe weight

Answer 10

• Weight of an object is the pull of the earth on it
• It is a force
• Measured in Newtons (N)
• Has a direction i.e towards the earth
• Gets smaller as you rise up
• Weight can change

Question 11

Describe mass

Answer 11

• Mass of an object is the amount of matter in it
• Measured in grams (g) or kilograms (kg)
• No direction
• Mass is constant

Question 12

How do you convert mass to weight?

Answer 12

weight = mass x 10

Question 13

How do you convert weight to mass?

Answer 13

mass = weight ÷ 10

Question 14

How many times smaller is weight on the moon?

Answer 14

6 times