Question

Two balls are dropped from the top of a cliff at a time interval $\Delta$t = 2 s. The first ball hits the ground, rebounds elastically (essentially reversing direction instantly without losing speed), and collides with the second ball at height h = 55 m above the ground. How high is the top of the cliff?

Answer 1

consider the height of the tower to be $h$

so the first ball will take $t$ seconds to cover the distance of $(h-55)$ m and the second ball will take $t+2$ seconds to cover the same distance in that $2$ seconds the first ball will cover $110m$

so in the case of the first ball we have two types of motions upward and downward it will cover both the types of motions in equal time intervals so we get the initial velocity which is the final velocity for the distance of $(h-55)$ with which we get the distance of $h-55$ finally we get the awnser as $180m$