Two particles A and B of mass 2 kg and 3kg are thrown from the top of a tower such that A moves horizontally with vel. of 30m/s and B moves vertically up with vel. of 20m/s(g=10m/s^2).What is the acceleration of the centre of mass of the system?

1 Answer
Steve J.
Jan 4, 2018

The acceleration of the centre of mass of the system is #10 m/s^2#, downward.

Explanation:

The only force acting on the particles is the force of gravity. (We have to assume air drag is to be ignored in this question.)

When the net force acting on a body is its weight, it accelerates downward at the value of g. Whether particle B is going up or down does not change the acceleration from 10 m/s^2. The horizontal velocity of particle A continues to be 30m/s until it hits the ground. Newton's 1st Law (inertia) says so.

None of the numerical data provided in the question (except where the value of g was given) affects the value of the acceleration. Giving you that data is just noise.

I hope this helps,
Steve

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