tutor.eduforge
✦ Class 8 · Science
Force and Pressure
Have you ever wondered why a tiny thumbtack can hold up a big poster, but a flat hand can't push into a wall?
This lesson is not one of the free ones right now. Create a free account — it takes a few seconds, costs nothing, and opens 7 lessons plus your scores and doubts.
What this lesson covers
Step by step, in this order.
- 1Introduce the mystery: why a thumbtack easily goes into a board, but a finger pressing with the same effort doesn't.
- 2Define 'force' as a push or a pull. Explain that it always involves two things interacting.
- 3Explain what a force does: it can start motion, stop motion, or change the speed or direction of an object. Give examples like kicking a ball.
- 4Introduce 'contact forces'. Explain muscular force (e.g., lifting a school bag) and friction (e.g., a ball slowing down).
- 5Introduce 'non-contact forces'. Explain magnetic force (magnets attracting) and electrostatic force (comb picking up paper bits).
- 6Return to the thumbtack mystery. Explain that the difference isn't just force, but 'pressure'. Define pressure as force divided by area.
- 7Explain that the same force on a smaller area means more pressure. Use examples like a sharp knife cutting easily, and the thumbtack.
- 8Give more everyday examples of pressure: school bags with wide straps are more comfortable, and camels have wide feet to walk on sand.
- 9Explain pressure in liquids: it increases with depth. Give the example of a dam wall being thicker at the bottom.
- 10Explain pressure in gases: introduce 'atmospheric pressure'. Explain that it's huge, but we don't get crushed because our internal body pressure balances it.
How it looks
A real board, not a video.
This board is from a different Science lesson — yours will look like this. She writes and draws while she explains, and stops to check you followed.
Doubts this lesson clears up
- Why doesn't the huge atmospheric pressure crush us?
- How does a vacuum cleaner work if it just 'sucks'?
- How do fish survive under such high pressure deep in the ocean?
- Why does a balloon pop if you blow too much air into it?
- Is weight a type of force?
- Can a force happen without two things touching each other?
Give your child a better way to learn Maths & Science.
Interactive. NCERT-aligned. Any time, anywhere.