two blocks are connected over a pulley. The mass of block A is 8.7 kg and the coefficient of kinetic friction between A and the incline is 0.37. Angle θ of the incline is 31°. Block A slides down the incline at constant speed. What is the mass of block B?

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anonymous · Answer

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anonymous · Answer

want to Solve Tension in the chord in order to solve for mass B
Force friction acts up the ramp since block A is sliding down.
need to find the normal Force in order to determine the Force of friction.
we know the normal force to be Wcos(theta) by geometry.
The force of friction acting up the ramp is 0.37(8.7)(g)=Ff
we also need the force due to gravitation acting down the ramp knowing it to be Wsin(31) by geometry.
now sum up the forces in the x direction knowing the sum must be zero (constant velocity)

set up the coordinate system parallel to the ramp. negative being down the ramp

T+Ff-Wsin(31)=0
using the above calculations for Ff and W=mg you can determine the Tension in the rope.
If you draw a free body diagram at B you will notice that T will equal the Weight of B
or T=W ; T=mg
m=T/g

where m is the mass of B and your final answer.

anonymous · Answer

ahh my answer came up as 1.26kg...is that what you got?

anonymous · Answer

yep thats what i got.