A rocket moves forward by pushing the surrounding air backwards.

A block of mass 2 kg rests on a rough inclined plane making an angle of $$30^\circ $$ with the horizontal. The coefficient of static friction between the block and the plane is 0.7. The frictional force on the block is

A ship of mass 3 $$ \times $$ 10⁷ kg initially at rest, is pulled by a force of 5 $$ \times $$ 10⁴ N through a distance of 3 m. Assuming that the resistance due to water is negligible, the speed of the ship is

Two masses of 1gm and 4 gm are moving with equal kinetic energies. The ratio of the magnitude of their linear momentum is