Question

Two balls are thrown simultaneously, a vertically upward with the speed of 20 from the ground and vertically downward from a height of 40 m with the same speed and along the same line of action. At what points do the two balls collide?

Answer 1

Let ball be A and B then the relative velocity of B is 40 m/s and relative acceleration between them is also zero so , Now ball A is at rest and. B is moving upward with constant velocity and height of tower is 40 m.
from this we get that both ball will collide at 1 sec .
Now we can calculate the distance of collision from three equation of motion.