Experiment 1 — The Bed of Nails

Topic: Physics · Class 8 · Force and pressure: pressure = force ÷ area

Aim: Rest the 5 kg weight on the balloon without bursting it (keep the pressure below 50 kPa).

Daily: A camel’s broad feet stop it sinking into Thar sand, a sharp knife cuts because its edge has almost no area, and a school bag with wide straps hurts less than one with thin cords. Same force, different area.

Question: The same 5 kg weight rests first on one nail, then on 200 nails. The pressure on the balloon…

Exp: Pressure = force ÷ area. More area under the same force means far less pressure.

Exp: 1 pascal = 1 newton per square metre.

Exp: A thin edge has tiny area, so even a small force gives huge pressure.

Question: Why do tractors have wide tyres?

Exp: Larger contact area spreads the weight.

Question: A 200 N force on 0.5 m² gives a pressure of…