Question

(a) Give the (likely) value of the force of limiting friction.
(b) Why does the box stay at rest in the cases corresponding to fig (a) and fig (b)?
(c) Mark the direction of frictional force, and mention the kind of frictional force that comes into play in each case.​

Answer 1

Explanation:

I) = A force applied to the two surface exceeds the limiting friction,motion will occur. For two dry surfaces, the limiting friction is a product of the normal reaction force and the coefficient of limiting friction.

II) = An object in rest does not slide unless the force applied on it is more than limiting force .As in figure a & b, the applied force is less than limiting friction, i.e. 3F, therefore the box remains at rest.

III) =Frictional force is always in the opposite directions.Also, if you want move the boxes the force applied on the boxes be larger than the frictional force.

fig(a) –– Static friction .

fig(b) –– Static friction.

fig(c) –– Sliding friction .