Explain why
(a) A horse cannot pull a cart and run in empty space.
(b) Passengers are thrown forward from their seats when a speeding bus stops suddenly.
(c ) A cricketer moves his hands backwards when holding a catch.

Explanation

(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 the opposite direction on the feet of the horse The forward component of this reaction is responsible for motion of the cart In empty space there is no reaction and hence a horce cannot pull the cart and run .
(b) This is due to inertia of motion When the speeding bus stops suddenly lower part of the bodies in contact with seats stop The upper part of the bodies of the passengers tend to maintain the uniform motion Hence the passengers are thrown forward
(c) While pulling a lawn mower force is applied upwards along the handle The vertical componet of this force is downwards and increases the effective weight of the mower As the effective weight is lesser in case of pulling than in case of pushing therefore pulling is easier than pusing .
(d) While holding a catch the impulse received by the hands F `xx` t = change in linear momentum of the ball is constant By moving his hands backwards the cricketer increases the time of impact (t) to complete the catch As increases F decreases and as a reaction his hands are not hurt severely
.