# Conservation of Energy

1. Jun 15, 2014

### PVnRT81

1. The problem statement, all variables and given/known data

A shot putter throws her shot. At the moment the 4.00 kg weight leaves her hand, it as a velocity of 14.0 m/s and is 2.00 m above the ground. The weight reaches a maximum height of 6.50 m above the ground before falling back down.

What is the magnitude of the weighted ball's velocity at the peak of its trajectory?

2. Relevant equations

Ek = (0.5)(m)(v2)
Ep = (m)(g)(h)

3. The attempt at a solution

(0.5)(m)(v2) initial + (m)(g)(h) initial = (0.5)(m)(v2) final+ (m)(g)(h) final

(0.5)( 14 m/s)2 + (2 m)(9.8 m/s2) = (0.5)(v2) + (9.8 m/s2)(6.5 m)

Vpeak = 5.19 m/s

I don't know if this is correct... isn't the velocity at the peak supposed to be zero as all the energy is potential.

2. Jun 15, 2014

### PhysicoRaj

Yes, but when? What type of motion are you dealing with?

3. Jun 15, 2014

### PhysicoRaj

Hint: you mentioned a shot put.

4. Jun 15, 2014

### Staff: Mentor

Your approach is correct, but I don't see how you got that answer. Resolve for the velocity.

Note that the weight is not thrown vertically.

5. Jun 15, 2014

### PVnRT81

The peak velocity is 10.38 m/s.

6. Jun 15, 2014

### Staff: Mentor

That's better.