A barrier AB of length 12m is hinged at A. At the lower end, a horizontal spring keep the barrier closed. The height of the water is 6m and the width of the barrier is 5m. Water level is 4m below the hinge A. If minimum elongation of spring to keep the barrier closed is 1m, find the spring constant. [Neglect atmospheric pressure.]

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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