I am solving work and energy objective from HC Verma.I got a question in which I have a basic doubt.The question is total work done on a particle is equal to change in kinetic energy always.But,I think it was wrong bcz if a body falls from a inclined plane and its final velocity is 'v' and it moves through height 'h' ,then total work done =mv²/2+mgh.But,in the question it is mention that total work done is only equal to change in kinetic energy.So,the work done must only be equal to mv²/2,butfrom thisway I can't get the answer.Please correct me where I was wrong.

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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