Question

why is it advised to tie any luggage kept on the roof of a bus with a rope​

Answer 1

Answer:

When a bus travels, its motion cannot be uniform in practice. ... If any luggage kept on the roof of the bus is not tied with a rope, then it tends to move forward due to its inertia. In this process, it could fall off the bus. Therfore, it is advised to tie any luggage kept on the roof of a bus with a rope.

Answer 2

While the bus is moving, luggage tends to remain in inertia of motion state. When the bus stops, the luggage tends to resist the change and due to inertia of motion it moves forward and may fall off. That's why it is advised to tie any luggage kept on the roof of a bus with a rope.