Interesting angle of elevation problem

[steven1495]

Homework Statement

What is the angle of elevation of a projectile that travels THREE time horizontally its MAXIMUM height, on earth

g = 9.800m/s²

Homework Equations

Equation 1 - H = ((vsinθ)²)/2g

Equation 2 - R = 2v²((sinθcosθ)²/g

The Attempt at a Solution

I tried making 3x(equation 1)=equation 2, and letting v=5m/s, and then solving for θ, but I don't think I rearranged the equation properly. THE ANSWER IS FOR SURE 53.13°, I JUST HAVE TO SHOW HOW TO GET IT
Thanks for any help

 

[lewando]

Equation for range is not right.

 

[steven1495]

Equation for range is not right.

What is the equation for range? And could you help me with it?

 

[lewando]

R = 2v²sinθcosθ/g. That should get you going.

 

[steven1495]

i still can't figure it out

 

[lewando]

Nothing wrong with your original approach (3H = R). Show your work so you can more specifically show where you are having a problem.

 

[steven1495]

I don't need help with that one anymore, but if you could help me with a different problem, it would be great.

a)To what elevation must one go to decrease your "weight" to one sixteenth (1/16) of its "surface" value?

b) At the elevation calculated in part a), what is the period of this orbit?

G = 6.670x10^-11
R(earth) = 6.380x10^6
M(earth) = 5.98x10^24

 

[lewando]

You should start a new thread, following the template, listing all relevant equations, showing your work, etc.

 

[steven1495]

thats all i have, i have no idea how to solve it