Forces & energy

A force is simply a push or a pull that can start, stop, speed up, slow down, or change the direction of an object's motion. Friction is a force that opposes motion between two touching surfaces. Gravity is the force pulling objects toward the Earth. Energy isn't created or destroyed — it's transferred or transformed from one form to another, such as chemical energy in food transforming into kinetic energy when you move.

Key terms

Force:

A push or a pull.

Friction:

A force that opposes motion between two surfaces.

Gravity:

The force that pulls objects toward Earth.

Kinetic energy:

The energy of motion.

Questions

1. 1. A push or a pull is called a:

   • Force
   • Energy
   • Mass
   • Speed

2. 2. The force that pulls you back down when you jump is:

   • Friction
   • Gravity
   • Magnetism
   • Tension

3. 3. Riding a bike uses energy that originally came from the food you:

   • Ate
   • Smelled
   • Saw
   • Heard

4. 4. Which of these is an example of a force?

   • Colour
   • A push
   • Temperature
   • Sound only

5. 5. Rubbing your hands together creates heat because of:

   • Gravity
   • Friction
   • Magnetism
   • Light

6. 6. A ball rolling along the ground eventually stops mainly because of:

   • Magnetism
   • Friction
   • Light
   • Sound

7. 7. Energy of motion is called:

   • Potential energy
   • Kinetic energy
   • Chemical energy
   • Light energy

8. 8. A force that opposes motion between two surfaces is:

   • Gravity
   • Friction
   • Magnetism
   • Tension

9. 9. Energy cannot be created or destroyed, only:

   • Deleted
   • Transformed or transferred
   • Increased infinitely
   • Stopped

10. 10. The force that pulls objects toward Earth is:

    • Friction
    • Gravity
    • Tension
    • Magnetism

11. 11. Kinetic energy is the energy of:

    • Position
    • Motion
    • Stored chemicals
    • Light

12. 12. When you kick a ball, you are applying a:

    • Force
    • Sound
    • Colour
    • Smell

13. 13. The energy stored in food before you eat it is called:

    • Kinetic energy
    • Chemical energy
    • Light energy
    • Sound energy

14. 14. A car's brakes use which force to slow it down?

    • Gravity
    • Friction
    • Magnetism
    • Light

15. 15. A skydiver falling through the air experiences gravity pulling them down and _____ pushing up against them.

    • Friction (air resistance)
    • Magnetism
    • Light
    • Sound

16. 16. When you eat food, chemical energy is transformed into kinetic energy when you:

    • Sleep
    • Move your body
    • Sit still
    • Think only

17. 17. Why does a bike eventually stop rolling if you stop pedalling on a flat road?

    • Gravity pulls it down
    • Friction between the tyres, road and air slows it
    • Magnetism stops it
    • It runs out of colour

18. 18. A car uses fuel to drive. This is an example of chemical energy being transformed into:

    • Kinetic energy
    • Gravity
    • Magnetism
    • Nothing, it disappears

19. 19. Which statement about energy is TRUE?

    • Energy can be created from nothing
    • Energy can be destroyed completely
    • Energy can only be transformed or transferred, not created or destroyed
    • Energy never changes form

20. 20. A skater glides further on ice than on concrete mainly because ice has:

    • More friction
    • Less friction
    • More gravity
    • Less gravity

21. 21. Two ice skaters push off each other and both move apart. This shows that forces:

    • Only affect one object at a time
    • Come in pairs and affect both objects
    • Don't exist on ice
    • Only work on land