Engineering
Physics
Thermal Expansion
Question

A rectangular piece of metal 3 cm high by 6 cm wide has a hole cut in its centre 1 cm high by 4 cm wide as shown in the diagram. As the metal is warmed from 0 °C to 100 °C, what will happen to the dimensions of the hole?

both height and width will increase

both height and width will decrease

height will decrease while width will increase

both height and width will remain unchanged

JEE Advance
College PredictorLive

Know your College Admission Chances Based on your Rank/Percentile, Category and Home State.

Get your JEE Main Personalised Report with Top Predicted Colleges in JoSA

Solution

When a metal object is heated, it expands uniformly in all directions due to thermal expansion. The linear expansion is given by ΔL = αL₀ΔT, where α is the coefficient of linear expansion, L₀ is the original length, and ΔT is the temperature change. This principle applies to any part of the material, including the boundaries of a hole. As the entire metal piece expands outward, the hole also effectively expands. Therefore, both the height and width of the hole will increase.

Final answer: both height and width will increase