1. Oct 10, 2008

### pinkerpikachu

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

A 2.0 kg projectile is fired with initial velocity components Vox= 30 m/n and Voy = 40 m/s from a point on the earth's surface. Neglect all effects due to air resistance.

A) What is the kinetic energy of the projectile when it reaches the highest point in its trajectory?
B) How much work was done in firing the projectile?

2. Relevant equations
W=Fx
KE= 1/2mv^2
PE= mgh
W=KE

3. The attempt at a solution

To find the initial velocity, I took the components and did the math as thought it is a right triangle and got 50 m/s. What I don't understand about part A is that when the projectile is at the maximum height, it's only there for an instant and the velocity id zero, which should make the KE zero also correct?

but the answer is apparently 900J

I don't know how to find the highest point of the projectile's path, nor part B

Last edited: Oct 10, 2008
2. Oct 10, 2008

### Rake-MC

$$E_k = W$$