Time taken by same ball to return to the hands of juggler =
2u
g
=
2×20
10
= 4 s. So he is throwing the balls after each 1 s. Let at some instant he is throwing ball number 4. Before 1 sof it he throws ball. So height of ball 3 : h3 = 20 × 1 -
1
2
10(1)2 = 15 m Before 2s, he throws ball 2. So height of ball 2 : h2 = 20 × 2 -
1
2
10(2)2 = 20 m Before 3 s, he throws ball 1. So height of ball 1 : h1 = 20 × 3 -