Ajuggler tosses balls vertically to height h. to what height must they be tossed if they are to spend twice as much time in the air?

The ball must be tossed to a height of 4 times the initial height H

Explanation:

We have equation of motion S = ut + 0.5at²

A juggler tosses balls vertically to height H.

That is

      H = 0 x t + 0.5 x a x t²

      H = 0.5at²

To what height must they be tossed if they are to spend twice as much time in the air.

      H' = 0 x 2t + 0.5 x a x (2t)²

      H' = 2at² = 4 H

So the ball must be tossed to a height of 4 times the initial height H