- #1
e_burke
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Homework Statement
Block b with mass 5kg rests on block a with mass 8kg which in turn is on a horizontal tabletop. there is no friction between block a and the table top but the coefficient of static friction between block a and b is 0.75.A light string attached to block a passes over a frictionless pulley and c is suspended from the other end. what is the largest mass the block c can have so that a and b still slide together when the system is released from rest
Homework Equations
w=mg
fs=usmg
f=ma
The Attempt at a Solution
I figured i needed to work out what force is required to move a and b together
w=mg
w=(5+8)x9.8
=127.4N
I then worked out the static force
fs=usmg
= 0.75x5x9.8
=36.75
I then decided that this was the maximum force that the two blocks could be moved with
There for for c we know acceleration = 9.8
F=ma
36.75=mx9.8
m=3.75kg
im not sure if this is right as i don't think my logic makes much sense
any help would be much appreciated thank you very much