A boy throws a ball in air at ` 60^@` to the horizontal along a road with a speed of ` 10 m//s`. Another boy sitting in a car passing by observes the ball. Sketch the motion of the ball as observed by the boy in the car, If car has a speed of `(18 km //h)`. Give explanation to support your diagram.

Explanation

Consider the diagram below

The boy throws the ball at an angle of `60^(@)`.
`:.` Horizontal component of velocity `=4 cos theta`
`=(10m//s) cos 60^(@)=10xx(1)/(2)=5 m//s`.
Speed of the car=18km/h=5m/s.
As horizontal speed of ball and car is same , hence relative velocity of car and ball in the horizontal direction will be zero.
Only vertical motion of the ball will be seen by the boy in the car, as shown in fig. (b)