One More Accelerated Parallel Force

[ch3570r]

"For a 5.0 kg object on a horizontal surface that has a coefiicient of static friciton where us = 0.15 and a coefficient of kinetic friction where uk = 0.07, what is the parallel force necessary to accelerate the object at 12 m/s^2."

a) 53.6 N
b) 56.6 N
c) 60.0 N
d) 63.4 N
e) 67.4 N

I found that the normal force (FN) is 49 N. The max force is 7.35 N. However, I don't know how I would go about finding a force needed to accelerate an object. ...help...

 

[berkeman]

Which mu should you use if the object is moving? The force in F=ma will be the combination of the frictional force and the force required to accelerate the mass...

 

[ch3570r]

by using F=ma, 5*12, I get 60. For the uk force, I multiplied 49*.07. then uk force + force = 63.4, answer D