Weight. The earth exerts a force on everything This force is called gravity What does gravity do? Hold your pen up and then let go Why does this happen.

Weight

Weight

The earth exerts a force on everything This force is called gravity What does gravity do? Hold your pen up and then let go Why does this happen

Weight The force the earth exerts on me is

called my weigh

The weight of a body is the force pulling it towards the center of the earth

Like all forces, weight is measured in newtons

Weight So what is your weight, how do you

measure your weight

We are all made of matter, some people have a grater matter than others

The more matter an object has the greater will be the force acting on it

A block of lead would have a greater mass than a block of wood of equal size

Force of gravity acting on the block of lead would be greater than the force of gravity acting on the block of wood.

The block of lead has a greater weight

So the weight of a object is determined by two things the mass of it, and the fore of gravity acting on it

Weight Does your weight change when your in the

moon or space

Your weight changed because the pull of gravity on it changes

What is weight again = The force the earth exerts on an object

Will a litre of milk weigh the same on the earth, moon and space

Weight The litre of milk will be 6

times lighter on the moon compared to earth

The moon is one-sixth the size of the earth

The force of gravity acting on an object is one-sixth, of the force acting on earth

The moon has a force of 1.67 on 1kg

The litre of milk will be weightless in space

Your weight is zero in space, that’s why you can float because there is no force of gravity acting on you

Things also wheigh less on the top of a mountain

Instead of a force of 10 N it would be 9 N

Class Activity

Do calculation 1, 2, 3, 6, 6 minutes

Calculations 4, 5 homework

Calculations 1

A litre of milk (1kg) on the earth weighs

1kg x 10N = 10 N/kg A litre of milk on the moon weighs

1 kg x 1.67N = 1.67 N/Kg A litre of milk in space weights

1 kg x 0 = 0 N/kg A litre of milk on the top of a mountain weighs

1 kg x 9N = 9 N/Kg

Calculation 2

What is the object weighed 600kg, what would it weigh

Earth= 600 kg x 10N = 6000 kg/N Moon= 600 kg x 1.67N = 1002 kg/N Space= 600 kg x 0N = 0 kg/N Mountain= 600 kg x 9N = 5400 kg/N

Is it still milk inside

Is it still a litre

So this states that mass stays the same

If you are standing on the earth , moon and space you have the same mass but your weight changes

Recap = Mass & Weight

Mass Measured in

kilograms (kg) Is fixed, never

changes Is a fixed property of

all things, like length or volume

Weight Measured in Newtons

(N) Varies, depends on

where you are Is a force or a pull on

something

Calculation 3

An object of mass 50 kg has a weight of ___________ on earth

1kg = 10 N50 kg = 500N Answer 500N

Calculation 6

The mass of a man who weighs 550 N on earth is ___________

1 kg = 10 N ? Kg = 550N Answer 55 kg

Where would I weigh more?

Long Jump Record

Why did Bob Beaman’s 1972 long jump record (8.9 metres) last until 1991?

The Olympics were held in Mexico city….he weighed less!

Homework calculations 4 and 5

An astronaut has a mass of 124 kg

His weight on earth is 1240 kg/N, on the moon is 207.08 kg/N and inouter space is 0 kg/N. His mass , unlike his weight never varies wherever he is

Calculating Weight 5

Find the weight of a 250g bag of biscuits Solution: First change the mass to kg 250g = 0.25 kg (250g ÷ 1000) Now, F = 0.25kg * 10 m/s2

= 2.5 kg/m2

= 2.5 N