Conservation of Energy problem.

[cyspope]

Homework Statement

A 0.030-kg bullet is fired vertically at 200 m/s into a 0.15-kg baseball that is initially at rest. How high does the combined bullet and baseball rise after the collision, assuming the bullet embeds itself in the ball?

Homework Equations

m₁v₁ + m₂v₂ = (m₁ + m₂) v'

The Attempt at a Solution

0.030 kg * 200 m/s + 0.15 kg * 0 m/s = (0.030 kg + 0.15 kg) v' = 6 = 0.18 v'
v' = 33.333 m/s
$$\Delta$$p = m(v_f-v_o) = 0.18 kg (33.333 m/s) = 5.999 = 6 kg * m/s

Ok, this is what I did so far. Even though I know the velocity of the bullet + ball, I don't know how high it went up because I think I need to know the time or acceleration to find x, which is height.

Please help me what to do next.

 

[Delphi51]

The acceleration is -9.81 m/s².

 

[cyspope]

but I don't know the time.

 

[Redbelly98]

Take a look at the kinematic equations for constant acceleration. One of them will work here.