Posted by Henry on .
If the coefficient of kinetic friction between a 35 kg crate and the floor is 0.30, what horizontal force is required to move the crate at a steady speed across the floor? What horizontal force is required if μk is zero?

Physics 
Henry,
a. Fc=m*g = 35kg * 9.8 N/kg = 343 N @ 0o
= Force of crate.
Fp = 343*sin(0) = 0 = Force parallel to
floor.
Fv = 343*cos(0) = 343 N. = Force perpendicular to floor.
Fk = u*Fv = 0.3*343 = 103 N. = Force of
kinetic friction.
Fn = FxFpFk = ma.
Fx  0  103 = m*0 = 0
Fx = 103 N. = Hor. force applied.
b. Fx  Fp = 0
Fx  0 = 0
Fx = 0.