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

A projectile is launched at a 60° angle above the horizontal on level ground. The change in its velocity between launch and just before landing is found to be Δv^{→} = v^{→}_{landing} _ v^{→}_{launch} = -20 y^{^} m/s .

What is the initial velocity of the Projectile ?

What is its final velocity just before landing ?

**2. Relevant equations**

Δv^{→} = v^{→}_{landing} _ v^{→}_{launch} = -20 y^{^}

m/s .

**3.The attempt at a solution**

I considered :

V_{o}x + V_{f}x = 0 and V_{o}y + V_{f}y = -20

knowing that V²_{f}y – V²_{o}y= -2g (Y_{f}-Y_{o}) But I couldn’t go further

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

**2. Relevant equations**

**3. The attempt at a solution**

http://ift.tt/1hU9Mzj