Question

You toss a tennis ball straight upward. At the moment it leaves your hand it is at a height of 1.5 m above the ground, and it is moving at a speed of 6.4 m/s.When the tennis ball is at a height of 2.2 m above the ground, what is its speed?

Answer 1

the ball's speed is being converted to gravitational potential energy

1/2 m 6.4^2 =
... m g (2.2 - 1.5) + 1/2 m v^2

6.4^2 = 1.4 g + v^2

Answer 2

v = Vi - 9.81 t

h = Hi + Vi t -4.9 t^2

====================
2.2 = 1.5 + 6.4 t - 4.9 t^2
solve quadratic for t
then
v = 6.4 - 9.81 t