# Projectile Help

1. Feb 14, 2010

### rajesh.msen

Hi to all,
I have a problem in projectile motion.I need the angle of elevation.I know the launch point its greater than the target,I know the destination point where it should land,i know the speed it travels(its option for users to select the speed between (60 - 100),I need the angle of elevation to reach the destination point.
Ex : Angle of elevation differs based on the value of the variable speed.I not good in maths and very new to physics.Any one help me to solve this problem.Even tell me if the solution is not exit.

---Rajesh---

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

2. Relevant equations

3. The attempt at a solution

2. Feb 15, 2010

### tiny-tim

Welcome to PF!

Hi Rajesh! Welcome to PF!

Write equations for the x and y components separately.

For x, remember that the x component of velocity is constant.

For y, use the standard constant acceleration equations.

3. Feb 16, 2010

### rajesh.msen

4. Feb 16, 2010

### tiny-tim

Hi Rajesh!

(btw, no need to PM me … everyone gets automatic email notification of any reply to a thread that they've contributed to )

The question gives you vi (but not its direction), and x and y.

So call the time t, and call the direction θ, so that the initial components of velocity are vicosθ horizontally and visinθ vertically.

Then use the standard constant acceleration equations for the horizontal direction (a = 0) and the vertical direction (a = -g) separately: that gives you two equations, from which you can eliminate t, so you get one equation for θ.