Egypt Primary 5 Science, Week 24: Pushes, pulls and magnets

Shadows, forces and gravity

Week 24 · Theme 4 Change and Stability, Unit 4 Patterns in the Sky: Get Started, Unit Project Preview, Concept 4.1 Effects of Gravity (A) · 3 lessons

Pushes, pulls and magnets

Discovery Education Science P5: Term 2, Unit 4, pp. 104–111

GoalName pushes and pulls as forces, and give examples of magnetic and static forces.

New words

force · a push or a pull on an objectmagnetism · the force of a magnet, which can pull or pushstatic electricity · a small electric charge on a surface, for example on a rubbed balloon

Explanation

Things do not start, stop or change direction by themselves. Something pushes or pulls them, and a push or a pull is a force. You use a force to kick a ball, open a door or lift a bag. Some forces are weak, like a toy truck being pushed, and some are strong, like a real truck. Forces also have a direction. A magnet can pull a paper clip toward it, because magnets attract some metals such as iron and steel. Two magnets can pull together or push apart. If you rub a balloon on dry hair, it gets a static charge and can pull on small bits of paper or stick to a wall. Wind pushes the blades of a wind turbine, a spring pushes back when squeezed, and gravity pulls a dropped glass to the floor. In all these cases a force is the cause and a change in movement is the effect.

Worked examples

Mina pushes a heavy shopping cart. A big push makes it speed up quickly, and a small push moves it slowly. The size of the force changes how the cart moves.

Two bar magnets are set end to end. Unlike poles pull together, like poles push apart. The picture shows two magnets with the same poles facing each other. Which way will they move? They push apart.

Hana rubs a balloon on her dry hair and holds it near a few tiny bits of paper. They jump up to the balloon. The rubbed balloon has a static charge that pulls on light things. It works best on a dry day.

Class activity

Force hunt (a grown-up helps; keep magnets away from phones, cards and computers). Test five things with a small magnet: a steel paper clip, an iron nail, an aluminium foil piece, a plastic ruler and a pencil. Write which are pulled. Then rub a balloon on dry hair and see which tiny paper bits it lifts. Count how many paper clips a magnet picks up in one go, three times, and write the counts.

Practice

Is each a push or a pull? Kicking a ball; a magnet lifting a paper clip.

Magnet A picks up 8 paper clips and magnet B picks up 5. How many more does A pick up?

Which of these will a magnet pull: an iron bolt, a plastic ruler or a steel paper clip? Say the letters.

Give one example of a force that is neither a push by your hand nor a pull by a magnet.