# Very vague question about projectile launch angle

1. Jan 26, 2006

### scavok

The launching speed of a certain projectile is 5.2 times the speed it has at maximum height. What is the elevation angle at launching?

Could someone just give me a starting point or a hint in the right direction?

I know that the horizontal velocity doesn't decrease, and the vertical velocity is 0 at the maximum height. I can't put it together though; it seems like there isn't enough information given. How can you possibly tell by how much of a factor the speed is being affected by the vertical velocity, when you don't know the horizontal velocity?

2. Jan 26, 2006

### Psi-String

Maybe you can assume the magnitude $$V$$ of the lunching speed and find the relation between it and the horizontal velocity.

Hint: use trigonometry

Last edited: Jan 26, 2006
3. Jan 26, 2006

### andrevdh

At the maximum height the y component of the velocity is zero, therefore the speed at maximum height is only the x-component of the motion. The x-component of the velocity stays the same throughout the motion.