A ball is thrown straight upward and returns

to the thrower’s hand after 2.3 s in the air. A
second ball is thrown at an angle of 60◦ with
the horizontal.
At what speed must the second ball be
thrown so that it reaches the same maximum
height as the first? The acceleration of gravity
is 9.8 m/s
2
.
Answer in units of m/s

1 answer

2.3/2 = 1.15 seconds to go up

0 = Vi -4.9 t = Vi - 4.9*1.15
Vi = 5.365 m/s initial speed up

the second ball must have same initial vertical component of velocity = 5.365 m/s

Vi sin 60 = 5.365
so
Vi = 6.51 m/s