Mass, weight & gravityLO: To understand the difference between weight and mass and the effect of gravity.

Starter…

1 Tonne

Which would you rather have fall on

your head?

WHY?

1 Tonne

Feather & BrickThe feather weighs less than the brick but a tonne of feathers weighs the same as a tonne of bricks.

There will be other students that have the same weight as you but you may be different heights and a different gender.

Q) Which one would fall faster if dropped from the same height?

Battle of the BrainsYears ago an Italian scientist; Galileo thought that objects would fall at the same speed when dropped at the same height. He tested his method by dropping two cannon balls from the leaning tower of Pisa. The cannon balls were made of the same material but one weighed 10lbs and the other was 1lb.

The Greek philosopher Aristotle thoughtthat heavy objects fell faster than lighter objects.

WHO DO YOU BELIEVE WAS RIGHT?

You’re wrong Galileo!

Time to bust a myth!Watch the following video and see if you’re theory was correct…

Galileo Vs. Aristotle

So…

The myth-busters found out that in a normal atmosphere (on earth) air resistance slows down the fall of lighter objects.

Heavier objects are able to overcome or ‘beat’ the air resistance better than lighter objects.

Removing the air (creating a vacuum) removes the friction faced by falling objects.

What is mass?Mass is different from weight!

Mass is a measurement of how much of something there is. Mass is measured in grams and kilograms.

Weight a minute…Weight is a measurement of force…Force is always measured in Newtons (N)

Weight (N) = Mass (Kg) X Acceleration of Gravity

Mass = 1000Kg

Acceleration of gravity: 9.8 m/s

What’s my weight?(in Newtons!)

Calculate the weight!

Moon: Gravity = 1.6 Saturn: Gravity = 10.4 Mars: Gravity = 3.7

Neptune: Gravity = 11.5 Jupiter: Gravity = 24.9 Venus: Gravity = 8.8

1,600 N 10,400 N 3,700 N

8,800 N 24,900 N 11,500 N

The effect of gravity

Gravity is a force that ‘pulls’ objects towards the center of the earth. That’s why you’re feet are on the floor…

Gravity everywhere…

Gravity pulls everything into the center of the Earth no matter where you are!

Weight changes, mass doesn’t!

I’m always going to be 1,000Kg

No matter where I am! But my weight (force) can change when the

force of gravity changes.

Unless he eats me! then his mass will increase!

Defying gravity?When you jump or throw a ball in the air you are NOT defying gravity but just exerting a force greater than gravity for a short time. Gravity always wins because you will always land.

Quick Quiz1) Mass is measured in grams and kilograms.

2) Weight is the same as mass.

3) Gravitational forces change on other planets.

4) You weigh less on the moon.

5) Your mass changes in space.

FALSE

FALSE

TRUE

TRUE

TRUE

Discuss with a friend for 2 minutes then answer with your

planners.