- Define and explain Friction: Friend or Foe? in your own words
- Use key terms such as friction accurately
- Apply what you have learned to new examples and questions
- Avoid the common mistakes learners make with this topic
This lesson focuses on Friction: Friend or Foe?: discovering how friction slows moving things down and when that is useful.
Discovering how friction slows moving things down and when that is useful.
Key ideas
Friction opposes motion
When a toy car rolls across carpet it slows down much faster than on a smooth floor, because the carpet creates more friction. Friction always pushes back against the direction of movement. Without friction, walking on ice would be impossible — your shoes would just slide.
Forces change how things move
A stationary object stays still until a push or a pull acts on it. A moving object keeps going in a straight line until a force changes its speed or direction. The bigger the push, the bigger the change — a gentle tap nudges a ball, while a hard kick sends it flying.
Key term — friction: The force that slows things down when two surfaces rub against each other, like shoes gripping the ground.
Why does a sledge slow down on flat snow?
Friction between the sledge and the snow opposes its motion and slows it down.
Answer: Friction between the sledge and the snow opposes its motion and slows it down.
- Saying gravity pushes things down Gravity pulls things towards the Earth — the Earth attracts the object, so 'pull' is the correct word.
- Thinking friction only happens on rough surfaces Friction acts between any two rubbing surfaces, including smooth ice — there is just less of it.
Practice
Yes — a bigger push gives the car more speed, so it travels further before friction stops it.
Gravity pulls the marble downwards once it is no longer supported by the table.
Answers vary: opening a door or drawer, pulling on socks, tugging a zip. A pull moves something towards you.
A push — your foot shoves the ball away from you.
Quick check
Which of these best defines "friction"?
- Friction: Friend or Foe?: discovering how friction slows moving things down and when that is useful.
- Friction opposes motion: When a toy car rolls across carpet it slows down much faster than on a smooth floor, because the carpet creates more friction.
- force: A push or a pull.
- Watch out for: saying gravity pushes things down