9:00:00 AM (44%) Problem 4: A block with a mass or·76 kg is placed on a ramp. Th
ID: 1585347 • Letter: 9
Question
9:00:00 AM (44%) Problem 4: A block with a mass or·76 kg is placed on a ramp. The ramp has an incline of 0-27.9 degrees from the horizontal. The static coefficient of friction between the block and ramp is .·0.255, and the kinetic coefficient of friction between the block and ramp is Pk-a134. A force, F, is exerted on the block as shown. Note that the force F is parallel with the ramp. stationary on the ramp? Grade Summary Potential 100% sino cotan() cos0tan0 asin) Attempts remaining: (% per attempt) detailed vievw acotan sinh0 ODegrees O Radians -33% Part (b) what is the largest value (magnitude) for the force, F block stationary on the ramp? in Newtons that can be exerted on the block while still holding the 33% Part (c) what value (magnitude) for the force, F is needed to move the block up the ramp at a constant speed?Explanation / Answer
If block moves downwards, frictional force acts upwards
Fnet = 0
F + fs = Fg
F = Fg - fs
F = m*g*sintheta - us*m*g*costheta
F = 9.76*9.8*sin27.9 - 0.255*9.76*9.8*cos27.9
F = 23.2 N
part (b)
If block moves upwards , frictional force acts down the incline
Fnet = 0
F - Fg -fs = 0
F = Fg + fs
F = 9.76*9.8*sin27.9 + 0.255*9.76*9.8*cos27.9
F = 66.3 N
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part(c)
If the block moves at constant speed
acceleration = 0
Fnet = F - Fg - fk
from newtons second law
Fnet = m*a
F - 9.76*9.8*sin27.9 - 0.134*9.76*9.8*cos27.9 = 0
F = 56 N
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