# physics

posted by on .

A dockworker loading crates on a ship finds that a 20 kg crate, initially at rest on horizontal force to set it in motion. However, after the crate is in motion, a horizontal force of 60 N is required to keep it moving with a constant speed. Find the coeffiecints of static and kinetic friction between crate and floor.

Work:
75N=(20kg)a a=3.75m/s^2
60N=(20kg)a a=3m/s^2

I am not sure if I am starting it correctly. How would I solve this problem?

• physics (typo) - ,

A dockworker loading crates on a ship finds that a 20 kg crate, initially at rest on horizontal surface requires a 75N horizontal force to set it in motion. However, after the crate is in motion, a horizontal force of 60 N is required to keep it moving with a constant speed. Find the coefficients of static and kinetic friction between crate and floor.

• physics - ,

No, friction= mu*m*g
75=mu*20*9.8 solve fro mu static
50=mukinetic*20*9.8 solve for mu kinetic

• physics - ,

coefficient of friction = force app (F)/ Friction (9.8*20)