Pascal's Superpower

Why it matters

A mechanic presses a pedal-sized piston with one hand, and a car rises into the air. No gears, no pulleys — just trapped liquid doing what Pascal promised in 1653.

The idea in plain words

The hydraulic bargain. Tap the terms.

F₂ = F₁ × A₂/A₁

Brake pedal piston 2 cm², wheel pistons 40 cm² each. Pedal force 100 N → force per wheel?

2000 N at each wheel — and equal at all wheels, which is the safety point

• the principle: Pascal's law — pressure applied to an enclosed liquid transmits equally to every part and wall
• the bargain: force multiplier — A₂/A₁ is your mechanical advantage — like a lever made of liquid
• no free lunch: the price — the small piston travels FAR for the big one's small lift — energy stays honest
• exam list: applications — hydraulic press, car brakes (equal braking at all four wheels!), jack, JCB arms
• F₂ = 100 × 40/2

Predict first

Push a piston of 10 cm² with 50 N. The pressure reaching a connected 1000 cm² piston is…

Pascal's law: enclosed liquids pass pressure on UNDIMINISHED in all directions. Same P × 100× the area = 100× the force.

• exactly the same pressure — so the big piston feels 5000 N — correct
• one-hundredth the pressure
• the same 50 N of force

What you do

Choose your pistons and lift the 10,000 N car with a 50 N push — the liquid does the multiplying.

Check yourself

Hydraulic machines use LIQUIDS rather than gases because liquids…

Compress a gas and your pedal-push disappears into squeezing it. Liquids pass it on whole.

In a hydraulic lift, the small piston moves 50 cm to raise the big one 1 cm. This is because…

Same volume shifts through both cylinders: A₁d₁ = A₂d₂ — the exact see-saw trade.

Car brakes use hydraulics mainly because…

Unequal braking spins a car. Pascal's 'undiminished, in all directions' is a safety feature.

• are nearly incompressible — the push arrives instead of squashing — correct
• are heavier
• are cheaper
• energy is conserved: small force × big distance = big force × small distance — correct
• liquid leaks
• Pascal's law fails for distance
• equal pressure guarantees EQUAL braking force at every wheel — correct
• oil is slippery
• cables are old-fashioned