Friction When the arrow flies from the bow, it eventually slows down, falls down and stops. When a ball is thrown into the air, it eventually stops going up and starts coming back down to the ground where although it might bounce a few times, it eventually stops. When you ride down hill on your bike and you want to stop before you hit the wall, you squeeze the brakes and eventually, good maintenance assumed, you stop. When the wind blows the sails the boat will move through the water. When the wind stops blowing, the boat will eventually stop What has surface got to do with friction? What has shape got to do with friction? What is friction? What is actually going on when the arrow stops, the balls drops or you don’t actually hit the wall?

Useful Words Friction Air resistance Water resistance Force meter Vocabulary Useful Words Friction The action of one push or pull acting against another push or pull where the result is fast transfer of energy resulting with heated surfaces and maybe sound as energy vibrates the air Air resistance Friction caused by a body moving through air Water resistance Friction caused by a body moving through water Force meter A piece of equipment for measuring force Newtons The units in which force is measured Surface area The face of a body

Force meters 3 Newtons 7 Newtons 5 Newtons 8.5 Newtons

Forcemeter reading in Newtons Using Force meters Try hanging different objects from around the classroom on the forcemeter. Write down the readings you get! Object Forcemeter reading in Newtons

Force against resistance This picture shows the same box being pushed on different surfaces.

Investigation: Which surface do objects slide on most easily? Which of these surfaces will a weighted box slide across most easily? A) Vinyl B) Wood C) Carpet When you have chosen, explain why you think this surface will be the easiest to slide across

Investigation (cont.) Investigation: How are you going to test this? “What variable are you testing? (the thing that changes)” “What variable will you change?” “What variables will remain the same to make it a fair test?” “What will you measure?” Record the results as a bar chart, ask for help if you’re unsure.

Tyres on a car Playground slide Goalkeeper’s gloves Shoe laces High and Low Friction Is it best for each of the following to have a rough or a smooth surface? Situation High Friction Low friction Tyres on a car Playground slide Goalkeeper’s gloves Shoe laces A drawer Ice skates Climbing rope

Which shape do you think will travel through the water the quickest? Water Resistance Which shape do you think will travel through the water the quickest? Why do you think this one will be the quickest? Test different shapes to see how quickly they move through the liquid.

Water Resistance movement water

Friction: the collision of forces brakes ice skates Rough: high friction Smooth: low friction tyres slide goalkeeper’s gloves drawers Friction: the collision of forces Air resistance- the opposing push of air molecules against on an object moving through air Water resistance- the opposing push of water molecules against on an object moving through air Big area: High resistance Non streamlined: High resistance Streamlined: Low resistance Small area: Low resistance dart streamlined car sail (boat) parachute person walking through water submarine fish boat