Forces

1
Forces

• Gravity
• Friction
• Up thrust
• Air resistance

2
Gravity

• Gravity is the force that pulls us towards the
  earth.

• It gives everything a weight

• if gravity didnt exist we would float around
  like astronauts in space

3
FRICTION

• What do you notice about the soles of your shoes?
  
• There are patterns of ridges which are designed
  to stop you from slipping.
• A force called friction is created when 2 or more
  surfaces rub together.
• The greater the friction the more the 2 surfaces
  grip.

Why does a tyre need friction?
4
Upthrust

• Have you ever wondered why most boats dont sink?
• A force called Upthrust is present in water. It
  counteracts the effect of gravity.
• Look at the upthrust on this ship. Where would
  gravity be?

upthrust
5
Air resistance

• Why isnt this glider falling straight to the
  ground?
• Air resistance is the force that allows things to
  fall slowly.
• What other sports or modes of transport rely on
  the force of air resistance?
• Could you draw arrows to show the air force?

gravity
Air resistance
6
Force yourself!

• What forces are in action in this picture?
• What could you use to show the type, strength and
  direction of forces?