A 2.5 kg block is initially at rest on a horizontal surface. A horizontal force
ID: 2276724 • Letter: A
Question
A 2.5 kg block is initially at rest on a horizontal surface. A horizontal force Fvec of magnitude 6.1 N and a vertical force Pvec are then applied to the block. The coefficients of friction for the block and surface are ?s = 0.36 and ?k = 0.24. Determine the magnitude of the frictional force acting on the block if the magnitude of Pvec is 8.0 N. Determine the magnitude of the frictional force acting on the block if the magnitude of Pvec is 10.0 N. Determine the magnitude of the frictional force acting on the block if the magnitude of Pvec is 12.0 N.Explanation / Answer
a) W= mg= 24.5 N, P =8 N
N = mg- p = 16.5 N
Fr = us * N = 0.36 *16.5 = 5.94 N
Horizontal force = 6.1 so block moves
Friction = uk * 0.24 * 16.5 = 3.96 N
b) Fr = us(mg-P) = 5.22 N
So kinetic friction acts
Fr = uk * 14.5 = 3.48 N
c) Fr = us*N = 0.36 * (24.5-12) =4.5
Horizontal force = 6.1 N
so kinetic friction acts
Fr = uk*N = 0.24 *12.5 = 3 N