This force can either push the block upward at a constant velocity or allow it t

Question

This force can either push the block upward at a constant velocity or allow it to slide downward at a constant velocity. The magnitude of the force is different in the two cases, while the directional angle is the same. Kinetic friction exists between the block and the wall, and the coefficient of kinetic friction is 0.290. The weight of the block is 47 N, and the directional angle for the force vector P is = 31°. Determine the magnitude of vector P when the block slides the following ways. (a) up the wall

Explanation / Answer

Since the block moves with constant velocity ,then the accelaration a= 0 m/s^2

i.enet force along the wall and perpendicular to the wall is 0 N

along the wall

0 = P*cos(31) - fk - m*g

fk is the kinetic frictional force = mu_k*P*sin(31) = 0.29*47*sin(31) = 7.01 N

m*g = 47 N

0 = P*cos(31)-(mu_k*P*sin(31))-m*g

P = m*g/(cos(31)-mu_k*sin(31)) = 47/((cos(31)-0.29*sin(31)) = 66.4 N

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