Question

A sledge moving over a smooth horizontal surface of ice at a velocity drives out on a horizontal road and comes to a halt as shown. The sledge has a length l, mass m and friction between runners and road is .

Answer 1

Coefficient of friction $=\mu$

Frictional force between road and sledge $=\frac{1}{2}\mu mg$

$\because\ as \ the \ length\ increases \ from\ 0\ to \ l\ force\ increases\ from\ \\0\ to \ \mu mg$

Work done against friction as the sledge shift completely on the road$=\frac{1}{2}\mu mgl$