Solved Problems: Thermal Physics

Thermal Physics (Science)

Solved Problems

Example 1

A container whose capacity is 70 ml is filled with a liquid up to 50 ml. Then, the liquid in the container is heated. Initially, the level of the liquid falls from 50 ml to 48.5 ml. Then we heat more, the level of the liquid rises to 51.2 ml. Find the apparent and real expansion.

Data:

 Level of the liquid L1 = 50 ml

 Level of the liquid L2 = 48.5 ml

 Level of the liquid L3 = 51.2 ml

 Apparent expansion = L3 − L1

 = 51.2 ml – 50 ml = 1.2ml

 Real expansion = L3 − L1

 = 51.2 ml – 48.5ml = 2.7ml

 So, Real expansion > apparent expansion

 Example 2

 Keeping the temperature as constant, a gas is compressed four times of its initial pressure. The volume of gas in the container changing from 20cc (V1 cc) to V2 cc. Find the final volume V2.

Data:

Initial pressure (P1)= P

Final Pressure (P2) = 4P

Initial volume (V1) = 20cc = 20cm3 Final volume (V2) = ?

Using Boyle's Law, PV = constant P1V1 = P2V2