Iron rim is made slightly smaller than the wooden wheel

• GC Others

Iron rim is made slightly smaller than the wooden wheel. The rim is usually heated before fixing into the wooden wheel, because on heating the iron rim

1. expands and fits onto the wooden wheel.
2. contracts and fits onto the wooden wheel.
3. no change in the size takes place.
4. expands first, then on cooling contracts and fits onto the wooden wheel.

Answer

On heating the iron rim, it expands first, then on cooling it contracts and fits onto the wooden wheel. Expansion occurs on heating whereas contraction occurs on cooling.

The correct option is D.