A piece of glass is being lifted by a suction cup. Air is removed from the cup by a vacuum pump and a partial vacuum is created. Atmospheric pressure outside pushes the glass on to the cup. the area covered by the cup is 0.0025m2. The pressure inside the cup is reduced to 60,000 Pa. Atmospheric pressure outside is 100,000 Pa.
(i) Calculate the greatest weight of glass that can be lifted with this cup.
(ii) Name two alterations that would allow the suction cup to lift a heavier piece of glass.
You need to turn this into a forces question, using the equation Pressure = Force x Area
=> Force = Pressure/Area
Then get the force exerted on either side:
Due to atmospheric pressure = 250 N
Due to pressure inside suction cup = 150 N
Net Force = 100 N
Max weight lifted with 100 N
100 = mg
m = 15.3 kg
Increased surface area