Question

A $\frac{1}{2}\mathrm{kg}$ sheet of tin sinks in water but if the same sheet is converted into a box or boat, it floats. Why?

Answer 1

A tin sheet sinks in water because the density of tin is higher than water. But the tin box or boat floats on water because of the trapping of large amount of air, whereby the average density of tin box or boat becomes lower than water.