Newton’s 2^nd law states that - “the rate of change of linear momentum of a body is directly proportional to the external unbalanced force applied on the body and motion takes place in the direction of the force”.

But in cases like this --

Eg. – when we pull a cart with a rope we are applying a force in inclined direction toward’s us but the movement of cart is in horizontal direction.

Why this is so?

Another eg. – when we take the case of torque, the force applied is in the direction perpendicular to the body but it is moving in horizontal direction.

Why this is so?

Three identical balls are placed on a frictionless horizontal surface touching each other. They stick to each other because of adhesive. Another ball of same radius and mass m is placed over the void created by the three balls. Find the forces applied by the balls kept on the floor to each other if the system remains in equilibrium.

A car loaded with water having total mass 1000 kg moves on a straight horizontal Road starting from rest under the action of a force of 100 Newton. The water spills throw a small hole in the bottom at a rate of 0.1 KG per second the velocity of cart after 300 seconds is nearly.

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