To test quality of tennis ball, u drop it on the floor from height 4m. It rebounds to height of 2m. If the ball is in contact with the floor for 12ms, what is avge. acclrtn during that contact?(g=9.8m/s²)

Also is there any way we can use without applying the concept of collision or elasticity?

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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