A block of mass 0.1 is held against a wall applying a horizontal force of 5 N on the block. If the coefficient of friction between the block and the wall is 0.5, the magnitude of the frictional force acting on the block is:

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