Weight and MASS

What we want to achieve....

• Be able to recall the difference between mass and weight

• Be able to calculate you weight on other planets

• Be able to describe why the value of gravity is different on different planets

Brainstorm, what do we already know about gravity?

Gravity

Newton is famous for his theory of gravity

He actually worked out how the mathematics or the ‘rules or gravity’

The rules of Gravity affect everything that has mass so that meansYou, books, calculators, the planets, stars and teachers.

He is famous for the apple story

Although this probably never happened

All masses are attracted to each other

The force of gravity depends on the distance between the two masses and the Size (magnitude) of the two masses

FORCE is measured in NEWTONS (N)

Gravity pull all objects down at the same rate

Air resistance will slow some object but there is no air on the moon so...

MASS and WEIGHT are NOT the same thing!!!!!!!!!!

x Gravity

Mass is the same wherever you are as it is the amount of stuff (particles) that are in you

Weight is your mass multiplied by the gravitational pull of the planet you are on

Your weight is a force and is measured in Newtons

On Earth your weight is roughly 10x your mass

120kg 1200 N120kg x 10 =

On the moon the gravitational force is 6 time less than on Earth

x Gravity

120kg 200N120kg x 1.6 =

This is because the moon has 1/6 less mass than the Earth it has 1/6 less gravitational pull

The man has lost weight by going to the moon but what about his mass?

Place Weight of 1Kg Calculation Your weight (N)

Earth 10N

Mars 4N

Jupiter 23N

Pluto 3N

Uranus 11N

Venus 9N

Neptune 10.6N

On the moon 0.1N

In deep space 0N

If you know your weight in KG you can use that, otherwise use 50KG as your mass

Copy into your book the table above and calculate your weightRemember weight = mass x gravity

Conclusion-Where in the solar system would you weigh the most? How much would you weigh?Where in the solar system would you weigh the least? How much would you weigh?Trick QuestionWhat would your mass be on the moonWhat would your mass be on Pluto

Watch the video and answer these questions

1)What objects equal roughly 1 Newton?2)What is 1 Newton in Kgs?3)What is the force of gravity measured in?4)What is weight measured in?5)How much does your mass change when you are on the moon?6)Why do you weigh less on the moon? (refer to the mass of the moon)

Video review

Gravity and distanceThe Force of gravity decreases the further you move the two masses apart

The further you move away from the Earth the smaller the gravitational pull you will feel and your weight will go down.

Warning: THERE is gravity in space

Watch this videoOn zero gravity on

Earth

Force from Earth

ForceFromMoon

When will there be no resultant force on the spaceship?

1/6 mass of Earth

Apollo 131

2 3 45

Imagine you are a member of Apollo 13 describe your journey with respect to the gravitational pull of the Earth and moon.