$A$ passenger in a moving train tosses a coin which falls behind him. It means that the motion of the train is

In oil tankers,some space is left at the top while filling them. Explain why.

Two balls of the same size but of different materials,rubber and iron,are kept on the smooth floor of a moving train. The brakes are applied suddenly to stop the train. Will the balls start rolling? If so,in which direction? Will they move with the same speed? Give reasons for your answer.

An object experiences a net zero external unbalanced force. Is it possible for the object to be moving with a non-zero velocity? If yes,state the conditions that must be placed on the magnitude and direction of the velocity. If no,provide a reason.

$A$ body projected horizontally moves with the same horizontal velocity although it is under the action of the force of gravity,why?

Explain the following:
$(i)$ Why do we jerk wet clothes before spreading them on a line?
$(ii)$ Why does dust fly off when a carpet is hit with a stick?
$(iii)$ Why do fruits fall off the branches in a strong wind?
$(iv)$ Why does a pillion rider fall forward when the driver of a two-wheeler suddenly applies brakes?