Question

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:

• A. expands and fits onto the wooden wheel.
• B. contracts and fits onto the wooden wheel.
• C. no change in the size takes place.
• D. expands first, then on cooling contracts and fits onto the wooden wheel.

Answer 1

The correct option is D expands first, then on cooling contracts and fits onto the wooden wheel.

Metals expand on heating and contract on cooling:

• When the iron rim is heated, it expands and will have the same size as wooden wheels.
• On cooling the rims contracts to the size of the wooden wheel and get fixed on the wheels firmly.