A steel crate is pulled along a horizontal factory floor by a worker who exerts a…
PHYSICS · Multi-part · CBSE · Physics · Laws of Motion · Laws of Motion
Problem
A 50kg steel crate is pulled along a horizontal factory floor by a worker who exerts a constant horizontal force of 250N. The coefficients of friction between the steel surfaces are μs=0.45 and μk=0.30. Take g=9.8ms−2.
(i) Show, with calculations, whether the crate will start moving under the applied force.
(ii) If the crate moves, determine its acceleration.
(iii) Using a suitable kinematic relation, find the speed of the crate after it has travelled 10m, starting from rest.
(iv) The floor is now lightly oiled so that μk is reduced to 0.10 while μs remains unchanged. Repeat parts (ii) and (iii) for this case and comment on how lubrication affects the acceleration and the speed after 10m.