A block weighing 80N rests on a plane inclined at 20 degrees to the horizontal. The coefficient of static friction is 0.25, while the coefficient of kinetic friction is 0.15.(adsbygoogle = window.adsbygoogle || []).push({});

a) What is the minimum force F, parallel to the plane that will prevent the block from slipping down the plane?

b) What is the minimum force F that will start the blocking moving up the plane?

c) What force F is required to move the block up the plane at constant velocity?

a) I am confused about the difference between quesiton a and b? I don't know how to determine the minimum force that will prevent the block from slipping down the plane.

b) my equations

x-direction: Fapplied - Ffriction - mgsin theta = 0

y-direction: N - mgcos theta = 0

Ffriction = usN

Ff = us (mg cos theta)

Fapplied = us (mg cos theta) + mgsin theta

Fapplied = 18.79 + 27.36 = 46.15 N

N = mgcos theta

c)

Ffriction = ukN

Ff = uk (mgcos theta)

Fapplied = uk(mg cos theta) + mg sin theta

Fapplied = 10.4 + 27.36 = 37.76N

Please correct me if i made any mistakes

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# Grade 12 Physics - mass on an inclined plane (different question)

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