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1. The problem statement, all variables and given/known data

2. Relevant equations

Force equations/Kinetic equations

3. The attempt at a solution

FA = mA * 9.8 m/sec2

FA = FB

where FB is the force acting through the string from A to B

The forces on B are friction from the table, friction from C, and the force it takes to move B's mass at 0.8 m/sec2

FB = FfB + FfC + (1.4 kg * 0.8 m/sec2)

FfC = 0.3 * ( 0.6 kg * 9.8 m/sec2 )

FfC = 1.764 N

FfB = 0.25 * [ (1.4 kg + 0.6 kg) * 9.8m/sec2 ]

FfB = 4.9 N

FB = 1.764 N + 4.9 N + (1.4 kg * 0.8 m/sec2)

FB = 7.784 N

FA = 7.784 N

7.784 N = mA * 9.8 m/sec2

mA = 0.794286 kg ~ 794 grams

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# Homework Help: Calculating mass of a block

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