(a)We know that :
.
Frictional force is : Fr = m g sinθ = ( 23.0 * 9.8 * cos35 ) = 184.63 N
.
(b) We have :
.
m a = m g sinθ - μ mg cosθ
.
or μ mg cosθ = mg sinθ - ma
.
μ = ( mg sinθ - ma ) / mg cosθ
.
= ( 184.63 - 23.0 * 0.272 ) / (23.0 * 9.8 * cos35 )
.
= 0.966
.
Hope this helps u!