26.A horizontal force of 10 N is necessary to just hold a block stationary against a wall. The coefficient of friction between the block and the wall is 0.2. The weight of the block is:

27.A disc of mass 100 g is kept floating horizontally in air by firing bullets, each of mass 5 g with the same velocity at the same rate of 10 bullets/s. The bullets rebound with the same speed in opposite direction, the velocity of each bullet at the time of impact is:

28.When we kick a stone, we get hurt. Due to which one of the following properties of the stone it happens?

29.A marble block of mass 2 kg lying on ice when given a velocity of 6 m/s is stopped by friction in 10s. Then the coefficient of friction is: