I have 2 doubts,questions are in the attached image.

1. How can I find the acceleration of the individual blocks and the pulley(s) if the pulley itself is moved upwards?
2. In the second question, I used constraint relations to find the relations between accelerations. I got 2a₁ +a₂+a₃ = 0.After this , I also got the freebody equations. BUt while substituting for a₁ for eg, do I substitute as (-a₂ - a₃) /2 or (a₂+a₃) / 2, or this approach totally wrong. Please clarify.Thanks in advance.

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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