Physics Question

Question

You pull a 70-kg crate at an angle of 30 degrees above the horizontal. How hard do you have to pull to keep the crate moving with constant velocity if the ɱk = .4?

Answer 1

You pull a 70-kg crate at an angle of 30 degrees above the horizontal. How hard do you have to pull to keep the crate moving with constant velocity if the µk = .4?

Hello Sam,

The two components of weight are mg Cos theta Perpendicular to the plane and µmgSin Theta along the plane , against the direction of motion .

The Normal reaction is mgCos Theta

Theta = 30 degree given

For constant speed net force = 0

so mgsin30 +µmgCos Theta = Force Down the plane

µ= 0.4 ( Coefficient of Kinetic friction )

So to move with contant speed net force up the plane = mgsin30 +µmgCosTheta ,

F = 70*9.8*Sin30 +04*70*9.8*Cos 30 ( used g= 9.8m/s2, m= 70kg,Theta = 30)

F= 343+237.63 =580.63 N