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LBP
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Homework Statement
A block of wood is pulled by a horizontal string across a rough surface at a constant velocity with a force of 20 N. The coefficient of kinetic friction between the surfaces is 0.3. The force of friction is
A) impossible to determine without knowing the mass of the block.
B) impossible to determine without knowing the speed of the block.
C) 0.3N
D) 6N
E) 20N
I thought the answer would be A but it is apparently E but I'm not sure why.
Homework Equations
Static Friction= Mu(s)*(Normal Force)
Kinetic Friction=Mu(k)*(Normal Force)
Normal force=m*g
The Attempt at a Solution
From similar problems I started by trying to figure out if the block is moving by comparing the kinetic friction to the pulling force. However to get that I am missing the mass of the block (Kinetic friction=0.3*(m)*9.81). I am obviously thinking about this wrong. Any guidance?