A car manufacturer advertises that the brakes are so perfect that the car stops instantaneously. Comment.

Give an example of an accelerated body, moving with a uniform speed.

A train starting from rest picks up a speed of $10\, m s ^{-1}$ in $100\, s$. It continues to move at the same speed for the next $250\, s$. It is then brought to rest in the nert $50\, s$. Plot a speed$-$time graph for the entire motion of the train.

$(i)$ acceleration of the train while accelerating,

$(ii)$ retardation of the train while retarding,

$(iii)$ and the total distance covered by the train.

List two differences in tabular form between speed and velocity. When is a body said to have :
$(a)$ uniform velocity and $(b)$ variable velocity. How is the average velocity of a body is calculated when its velocity changes at a non$-$uniform rate ?

$(a)$ Differentiate between uniform linear and uniform circular motion.

$(b)$ Write any four examples of uniform circular motion.

$(c)$ Is uniform circular motion is accelerated motion ?