How does a hydraulic jack work and how do I work out the pressures involved?

(Draw hydraulic jack diagram using Pen tool) Firstly, we need the quation for pressure. Pressure is measured in Nm^2 which tells us that P=F/A. Where P is the pressure, F is the force in Newtons and A is the area in meters squared. When looking at the jack, we can see that we have 2 areas, one smaller one and one bigger one. But, since both sections of the jack are connected the pressure must be the same! Looking back at the equation for pressure, if P stays the same but A is bigger, F must be smaller so that P is constant. This means that if I apply a small force to the big area, a big force will act on the small area since P stays the same. This is why a hydraulic jack is also known as a force multiplier. If you want to work out exactly how big this force is, we can set P1=P2 and hence F1/A1=F2/A2 and then re-arrange to get F2=(F1/A1)*F2 (Please note at this point that I would draw this equation since typed equations can be very confusting as fractions get involved)

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Answered by Max Z. Physics tutor

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