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) It is easier to pull a lawn mower than to push it.
(d) A cricketer moves his hands backwards while holding a catch.

Hint: Newton’s three laws of motions can be used here to explain each of these situations. Inertia of motion keeps a body from changing its current state of motion. Pulling is easier than pushing.

Complete answer:
(a) A horse pushes the ground backward while attempting to move a cart. In turn, the earth exerts an equal and opposite reaction force on the horse's feet. The horse moves forward as a result of this response force. An empty space has no such response force. As a result, a horse cannot draw a cart and run in open space.

(b) This is due to motion inertia. When a fast bus comes to a quick halt, the lower half of a passenger's body that is in touch with the seat comes to a sudden stop. The top portion, on the other hand, prefers to remain in motion (as per the first law of motion). As a result, the passenger's upper body is propelled forward in the direction the bus was travelling.

(c) While pulling a lawn mower, an angle force is imparted to it. This applied force's vertical component acts upward. This decreases the mower's effective weight. When pushing a lawn mower, on the other hand, a force at an angle is applied to it. The vertical component of the applied force operates in the direction of the mower's weight in this example. This raises the mower's effective weight. Pulling the lawn mower is easier than pushing it in the first example because the effective weight of the lawn mower is lower.

(d) The cricket player moves his hand backward to reduce the pain. By moving his hand backward the ball will not come to an immediate stop, thus reducing

Note: Newton’s first law–The first law states that an object either remains at rest or continues to move at a constant velocity, unless it is acted upon by an external force.
Newton’s second law– the second law states that the rate of change of momentum of an object is directly proportional to the force applied, or, for an object with constant mass, that the net force on an object is equal to the mass of that object multiplied by the acceleration.
Newton’s third law – Every action has an equal and opposite reaction.