How Is the Acceleration of the Center of Mass Calculated with Differing Forces?

AI Thread Summary
The discussion revolves around calculating the acceleration of the center of mass for three balls with different masses and applied forces. The user initially applies the formula F/m = a incorrectly by not considering the individual forces acting on each ball. The correct approach involves calculating the net force on the system and dividing it by the total mass of the system. The acceleration of the center of mass is determined to be (1j - 2j)/6 m/s², confirming the correct magnitude. The clarification helps resolve the user's confusion regarding the calculation method.
Ridonkulus
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For some reason I can't seem to figure this question out. I get the feeling it's much easier than I'm making it. But here it is:

Ball 1, ball 2, and ball 3 have masses 1 kg, 2 kg, and 3 kg respectively, and are initially arranged at x = 1 m, x = 2 m, and x = 3 m respectively. y = 1 m for all three balls. Now suppose that a net force of 1 N is applied to ball 1 in the +y direction and a net force of 2 N is applied to ball 2 in the -y direction. The net force on ball 3 is zero. What is the magnitude of the acceleration of the center of mass of the three-ball system?

I've been using the formula F/m = a, where a is the acceleration of the center of mass. For F I've been using (1N-2N), and for mass I've been using (1kg+2kg+3kg). This gives me an answer of .1667 m/s^2, which I think is incorrect (because the formula doesn't take into account which part of the mass is moving in which direction with which force). Any help is greatly appreciated, thanks for taking the time to consider my question.
 
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You've come up with the right magnitude. The accelaration is (1j - 2j)/6 ms-2
 
Oh, ok thanks a lot!
 
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