Static and Kinetic Friction Problem, getting wrong answer?

[ADMINISTRAT0R]

A crate of oranges weighing 176 N rests on a flatbed truck 2.0 m from the back of the truck. The coefficients of friction between the crate and the bed are μs = 0.30 and μk = 0.20. The truck drives on a straight, level highway at a constant 6.3 m/s.

a. What is the force of friction acting on the crate?
I multiplied .30 X 176= 52.8. Online assignment says it's wrong?

frictional force= co of friction times Normal force

b. If the truck speeds up with an acceleration of 4.0 m/s2, what is the force of the friction on the crate?

magnitude:
Direction:

I simply used the kinetic friction value times the normal force and still got it wrong.


frictional force= co of friction times Normal force

(c) What is the maximum acceleration the truck can have without the crate starting to slide?

I got this right at 3 m/s

 

[ADMINISTRAT0R]

Alright, I got B and C, but I still can't get a.

 

[ehild]

The truck and the crate move together with a constant velocity along a straight line. Does the crate accelerate?

ehild