Please sir clear my little doubt in this question. It is from HC Verma .(I have only 1 problem why we write it as F1-m1a=Net force on m1.Why we can't write it as F1-kx1=Net force on m1 .From where this m1a come as it was acting on mass m1 and there was a spring between them so why it can't beF1-kx1=Net force on m1

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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