I have been stuck on this for a while....

A projectile's launch speed is five times it speed at maximum height. Find the launch angle.

Anybody have any clue how to do this?

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- Sep 16th 2008, 05:55 PMElite_Guard89Projectile Motion
I have been stuck on this for a while....

A projectile's launch speed is five times it speed at maximum height. Find the launch angle.

Anybody have any clue how to do this? - Sep 16th 2008, 07:50 PMmr fantastic
- Oct 1st 2008, 12:54 PMsu-z-q
- Oct 1st 2008, 01:10 PMGreengoblin
$\displaystyle \cos(\theta_{max}) = 1 $ (at maximum height), since this is the parabolic path of a projectile. So you have an unknwn velocity at maximum height, $\displaystyle v\cos(\theta_{max}) = v$, an, unknown initial velocity, $\displaystyle u=5v\cos(\theta)$, and an unknown angle $\displaystyle \theta$, which you need to find. I'd say there isn't enough information to find it. if you are assuming gravity of $\displaystyle -9.8ms^{-2}$, and have the final velocity, the launch and impact heights, then you could plug in the values for x and y, and solve simultaneous equations using the equations of motion.