When is an object in motion considered to be a point object ?
Define 'average speed'. An object moves with a uniform speed of $10\, m s ^{-1}$ for $5 s$ and then with a uniform speed of $5\, m s ^{-1}$ for $10\, s$. Find its average speed.
Name a physical quantity that essentially changes as a body moves.
Four cars $A$, $B$, $C$ and $D$ are moving on a levelled road. Their distance versus time graphs are shown in Fig. Choose the correct statement
All buses and cars these days are fitted with a speedometer, which shows the velocity of the vehicle. A device called odometer records the distance moved by the vehicle. If the reading on the odometer of a vehicle in the beginning of a trip and after $40$ minutes were $1048\, km$ and $1096\, km$ respectively, calculate its average velocity. Will the reading on the speedometer show this velocity when the vehicle is moving ? Support your answer with reason.