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 $km/h$?

Two cars $A$ and $B$ are travelling in the same direction with velocities $v_1$ and $v_2$ $(v_1 > v_2)$. When car $A$ is at a distance $d$ ahead of car $B$,the driver of car $A$ applies the brake,producing a uniform retardation $a$. There will be no collision when:

$A$ motor car moving at a speed of $72 \, km/h$ cannot come to a stop in less than $3.0 \, s$,while for a truck,this time interval is $5.0 \, s$. On a highway,the car is behind the truck,both moving at $72 \, km/h$. The truck gives a signal that it is going to stop in an emergency. At what distance should the car be from the truck so that it does not bump into (collide with) the truck? The human response time is $0.5 \, s$.

$A$ thief is running away on a straight road in a jeep moving with a speed of $9 \, m/s$. $A$ policeman chases him on a motorcycle moving at a speed of $10 \, m/s$. If the instantaneous separation between the jeep and the motorcycle is $100 \, m$,how long will it take for the policeman to catch the thief?

$A$ man on a rectilinearly moving cart,facing the direction of motion,throws a ball straight up with respect to himself.

Two particles start simultaneously from the same point and move along two straight lines,one with uniform velocity $v$ and the other with a uniform acceleration $a$. If $\alpha$ is the angle between the lines of motion of the two particles,then the time at which the relative velocity is minimum is given by: