A non zero ext. force acts on a systems of particles. The velocity and acceleration of the centre of mass are found to be v₀ and a₀ at an instant t. It is possible that

a)v₀=0, a₀=0 b)v₀₌ 0, a₀ ≠0 (c) v₀ ≠ 0, a₀=0

Answer given is b which is true but even (a) can be true e.g. if given net ext force provides torque...about the central axis then object would rotate leading to velocity and acc. of CM zero! So is a correct?

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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