Two wires are made of the same material and have the same volume. The first wire has cross-sectional area $$A$$ and the second wire has cross-sectional area $$3 A$$. If the length of the first wire is increased by $$\Delta l$$ on applying a force $$F$$, how much force is needed to stretch the second wire by the same amount?
Starting from the centre of the earth having radius $$R$$, the variation of $$g$$ (acceleration due to gravity) is shown by
A long spring, when stretched by a distance $$x$$, has potential energy $$U$$. On increasing the stretching to $$n x$$, the potential energy of the spring will be
With what velocity should an observer approach a stationary sound source, so that the apparent frequency of sound should appear double the actual frequency?