A 1000N crate is being pushed across a level floor at a constant speed by a force F of 300N at an angle of 20.0 degrees. (a) What is the coefficient of kinetic friction between the crate and the floor? (b) If the 300-N force is instead pulling the block at an angle of 20.0 degrees above the horizontal, what will be the acceleration of the crate? Assume that the coefficient of friction is the same as that found in (a).
2 answers
how is the angle measured?
N=mg±Fsinα
+ if α is measured below the horizontal
- if α is measured above the horizontal
(a) mgcosα =μN
μ = mgcosα/N
(b) ma=Fcosα –F(fr) =
= Fcosα – μN
Solve for ‘a’
+ if α is measured below the horizontal
- if α is measured above the horizontal
(a) mgcosα =μN
μ = mgcosα/N
(b) ma=Fcosα –F(fr) =
= Fcosα – μN
Solve for ‘a’
2 answers