State the reason for the following:
$(i)$ Some leaves may get detached from a tree if we vigorously shake its branch.
$(ii)$ It is advised to tie any luggage kept on the roof of a bus with a rope.

(N/A) $(i)$ This happens due to the inertia of rest. When the branch is shaken,it comes into motion,but the leaves tend to remain in their state of rest due to inertia. As a result,the connection between the leaf and the branch breaks,causing the leaf to detach.
$(ii)$ It is advised to tie luggage with a rope to prevent it from falling off due to inertia of motion or rest. When a bus suddenly starts or stops,the luggage tends to maintain its previous state of motion or rest,which could cause it to slide or fall off the roof.