The only vertical forces are weight and normal force, and they balance since the surface is horizontal. The horizontal forces are the applied force (uppercase F) in the direction the block slides and the frictional force (lowercase f) in the opposite direction.
Apply Newton's 2nd Law in the horizontal direction:
ΣF = ma
F - f = ma
where f = µmg
F - µmg = ma
F = m(a +µg)
F = (20 kg)(1.4 m/s² + 0.28(9.8 m/s²)
F = 83 N
Answer : When a person applies force and covers distance then the person is doing work on an object.
angular vel to tangential vel
v=r omega
v = 56 x 100/60 x 2 pi
v = 56x5/3x6
v=560m/s as estimate
100 revs, 5.00m