Question

1. A 10.0N cube with side lengths of 0.1m is hung from a scale and submerged completely into a bucket of water. What does the scale read when the cube is submerged in water?

2. An automobile tire is filled to an absolute pressure of 3.03x10^5Pa at a temperature of 30 C. Later it is driven to a place where the temperature is only -15 C.

If the wheel is made of steel and has an area of 0.20m^2 at the higher temperature, what is its change in the area when it is moved to the cold place? Does the area increase or decrease? ?????? = 12 × 10−6

Answer 1

1) Initial reading of scale when the cube is in air is 10 N.

When the cube is submerged completely into water, it experiences an upward force by the water which is buoyant force.

Due to this force the tension developed in the scale to balance the weight of cube required less.

Buoyant force = Fb =

Therefore, the scale reads = weight of cube - Fb = 10 - 9.81 = 0.19N [answer]

2) Coefficient of superficial or surface expansion = 2 * coefficient of linear expansion

=> .

By definition of expansion, the length , area and volume increases with rise in temperature and decreases with decrease in temperature.

Therfore, when moved to cold place, the area of tyre decreases.

And, change in area = [answer]