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JEE Main Physics question

PhysicsSystems of Particles and Rotational MotionJEE Main

At a certain instant of time, the mass of a rocket going up vertically is 100 kg. If it is ejecting 5 kg of gas per second at a speed of 400 ms⁻¹, the acceleration of the rocket would be (taking g = 10 ms⁻²)

Answer: (B)

Solution

Thrust = (dm/dt)v = 5×400 = 2000 N. Weight = 100×10 = 1000 N. Net upward force = 2000−1000 = 1000 N. a = 1000/100 = 10 ms⁻².

Question ID VK-152895