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## Homework Statement

Find magnitude of acceleration of system ABC. Masses of A, B and C are all equal and each has mass 2.00 kg. Let gravitational acceleration g = 9.81 m/s

^{2}. See figure below.

Disregard friction - castor, air, and surface.

## Homework Equations

Newtons 2nd law of motion:

F = m a (1)

## The Attempt at a Solution

The force on the whole system is gravity's effect on B and C (weight of B and platform C). Through (1):

F = (2)(2.00 kg)(9.81 m/s

^{2}) = 39.24 N

Acceleration on the whole system is then, under the above force: (Through (1) again):

a = (39.24 N)/[(3)(2.00 kg)] = 6.54 m/s

^{2}.

Obviously, the acceleration of A is directed horizontally, while B and C are accelerating downwards. Still, the acceleration of each objects will be the same, yet in their respective directions. It is this value which I am after.

Also, can someone less ignorant than I tell me if I am right in this:

Without other external forces (other than gravity), the system will never accelerate faster than 9.81 m/s

^{2}and the less the mass of A (and the larger the mass of B and C, equivalently), the closer the systems acceleration will be to 9.81 m/s

^{2}.

Thank you in advance and I apologize for the triviality of the problem :s