- #1

- 105

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## Homework Statement

Consider the system shown in the figure (Figure 1) . Block

*A*weighs 46.1 N and block

*B*weighs 28.7 N . Once block

*B*is set into downward motion, it descends at a constant speed.

http://session.masteringphysics.com/problemAsset/1038576/6/YF-05-54.jpg

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__

A

A

Calculate the coefficient of kinetic friction between block

*A*and the tabletop

μ= 0.623

__B__

A cat, also of weight 46.1 N , falls asleep on top of block

*A*. If block

*B*is now set into downward motion, what is its acceleration magnitude

## Homework Equations

F=ma

## The Attempt at a Solution

∑F in x direction of A: -F+T = ma

-μ92.1+T = 92.2/ 9.8 a

-.623(92.1)+T=9.4 a

∑F in y of A N-w = ma

92.2-9.4(9.8) = 0

∑F in Y of B T-w

T-2.93 (9.8) = 2.93 a

T= 28.7+2.93a

plug T into first equation: -.623(92.1)+28.7+2.93a = 9.4a

-.623(92.1)+28.7= (9.4-2.93) a

divide both sides

( -.623(92.1)+28.7) /9.4-2.93 = a

gives me wrong answer, where did I go wrong?