Answer:
Below
Step-by-step explanation:
First we need to find the normal force acting on the object :
Fn = mg
Fn = (450kg)(9.8)
Fn = 4410 N
Because the crate is sliding at a constant speed, there is no acceleration and therefore there is no applied force/the applied force is balanced with the friction according to Newton's 1st law.
In this case, there is applied force from the workers so the friction would have to equal the applied force in order for it to move at a constant velocity
Fa = Ff
450 + 310 = Ff
750 N = Ff
Now we can plug these values into the formula for the coefficient of friction
um = Fa / Fn
um = 750 N / 4410
um = 0.17
Hope this helps!