Pressure — return questions

1. calculate / deduce / suggest / explain

An upright piano stands on four small wheels on a soft wooden floor. Each wheel touches the floor over 2.0 cm². (a) Calculate the total area of the four wheels in m². (b) The floor dents under a pressure of more than 2 500 000 Pa. Calculate the largest weight that the floor can carry on these four wheels. (c) The piano weighs 2500 N. Use your answer to (b) to deduce whether the wheels dent the floor. (d) Suggest one thing to put under the wheels to stop the dents, and explain how it works.

(a) Total area in m²

(b) Largest weight

(c) Does the floor dent?

(d) How to stop the dents

2. deduce / explain / calculate

(a) Point X is 0.42 m below the surface of a tank of water. Point Y is 0.52 m below the surface of a tank of a liquid L. The pressure of the liquid is the same at X and at Y. Deduce whether liquid L is denser or less dense than water, and explain how you know. (b) Supplement. A pressure sensor is lowered into the Dead Sea, where the water has a density of 1240 kg/m³. It reads 30.4 kPa more than the pressure of the air. Take g = 9.8 N/kg. Calculate how deep the sensor is. Give your answer to 3 significant figures.

(a) Denser or less dense?

(b) Supplement: depth of the sensor