(a) While trying to pull a cart, a horse pushes the ground backwards with a certain force at an angle. The ground offers an equal reaction in opposite direction, on the feet of the horse. The forward component of this reaction is responsible for the motion of the cart. In empty space, there is no reaction and hence horse cannot pull the cart and run.
(b) This is due to inertia of motion possessed by the passengers in a speeding bus.
(c) While pulling a lawn mower, force is applied upwards along the handle. The vertical component of this force is upwards and reduces the effective weight of the mower as shown in figure (a). While pushing a lawn mower, force is applied downwards along the handle. The vertical component of this force is downwards and increases the effective weight of the mower, as shown in figure (b). As the effective weight is lesser in case of pulling than in case of pushing, therefore, pulling is easier than pushing. (d) While holding a catch, the impulse received by the hands, F × t = change in momentum of the ball is constant. By moving his hands backwards, the cricketer increases the time of impact (t) to complete the catch. As t increases, F decreases and as a result, the ball hurts his hands lesser.