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Pascal's Law & the Hydraulic Lift Worksheet
By the end you will: use Pascal's law and pressure = force ÷ area to explain how a hydraulic lift multiplies force.
A. Explore with the simulation
Lift the Car (1,200 kg). Change the piston sizes and fill in the table.
Small piston Big piston Push needed (N) Oil pressure (kPa) Pumps to reach 1 m 2 cm 20 cm 4 cm 20 cm 2 cm 40 cm Doubling the big piston's diameter changed the push by what factor? Why not just 2?
Why does a smaller push need more pumps?
B. Calculate (then check in the simulation)
Pistons have areas of 5 cm² and 250 cm². What force on the small piston holds up a 10,000 N car?
A 600 N person stands on one foot of area 150 cm². Find the pressure on the floor.
The small piston moves 20 cm down for each pump and the area ratio is 100. How many pumps lift the car by 10 cm?
C. Think it through
Why does a sharp knife cut better than a blunt one? Why do camels have wide feet?
Answer key (for teachers and parents)
- 2 & 20 cm: 117.6 N, 374 kPa, 401 pumps · 4 & 20 cm: 470 N, 374 kPa, 101 pumps · 2 & 40 cm: 29.4 N, 94 kPa, 1,601 pumps.
- The push became 4 times smaller, because area goes with diameter squared: 2² = 4.
- Each pump moves a little oil from the narrow cylinder into the wide one, which rises only a tiny amount. Less force means more distance: the work stays the same.
- F₁ = F₂ × A₁ ÷ A₂ = 10,000 × 5 ÷ 250 = 200 N.
- P = 600 ÷ 0.015 m² = 40,000 Pa (40 kPa).
- Each pump lifts it 20 ÷ 100 = 0.2 cm, so 10 ÷ 0.2 = 50 pumps.
- A sharp edge has a tiny area, so the same force gives a huge pressure. Wide feet spread the weight over a big area, so the pressure is low and they don't sink in sand.
Free to print and share for teaching. Made with the interactive simulation at jugnix.com/simulations/hydraulic-lift.