Two balls are projected upward simultaneously with speeds $40 \, m/s$ and $60 \, m/s$. The relative position $(x)$ of the second ball with respect to the first ball at time $t = 5 \, s$ is .......... $m$ [Neglect air resistance].

Two cars are moving in the same direction with a speed of $30\ km/h$. They are separated from each other by $5\ km$. $A$ third car moving in the opposite direction meets the two cars after an interval of $4\ minutes$. What is the speed of the third car in $km/h$?

On a foggy day,two drivers spot each other when $80\, m$ apart. They were travelling at $70\, km/h$ and $60\, km/h$. Both apply brakes simultaneously which retard the cars at the rate of $5\, m/s^2$. Which of the following statements is correct?

Train $A$ is moving along two parallel rail tracks towards north with speed $72 \ km/h$ and train $B$ is moving towards south with speed $108 \ km/h$. The velocity of train $B$ with respect to $A$ and the velocity of the ground with respect to $B$ are (in $ms^{-1}$):

Write the relation between instantaneous velocity and relative velocity for uniform motion.

$A$ car $A$ is travelling on a straight level road with a uniform speed of $60 \text{ km/h}$. It is followed by another car $B$ which is moving with a speed of $70 \text{ km/h}$. When the distance between them is $2.5 \text{ km}$,the car $B$ is given a deceleration of $20 \text{ km/h}^2$. After how much time will $B$ catch up with $A$ in hours?