(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A rifle, in which the initial velocity of the bullet is 460m/s, is aimed at a small target 800 metres away at the same height as the rifle. At what angle above the ground must the rifle be pointed so that it hits the target?

**

x = horizontal distance

t = time

V_{x}= horizontal velocity

g = gravitational acceleration

y = vertical distance

V_{yi}= initial vertical velocity

V_{yf}= final vertical velocity

**

so far I know:

x is 800m (given)

g = -9.81m/s^{2}, since the bullet is being pulled down by gravity

y = 0, because the bullet does not travel any vertical distance because it lands at the same height that it is shot at.

http://img144.imageshack.us/img144/1736/physicsproblem2bs1.jpg [Broken]

2. Relevant equations

vertical:

y = V_{yi}t + .5gt^{2}

y = V_{yf}t - .5gt^{2}

g = (V_{yf}- V_{yi})/t

V_{yf}^{2}= V_{yi}^{2}+ 2gy

horizontal:

V_{x}= xt

3. The attempt at a solution

I'm almost clueless on how to approach this one. I can't even see how there is enough info given to be able to solve it. all I have so far is a diagram

http://img464.imageshack.us/img464/4261/physicsproblemvf7.jpg [Broken]

Thanks in advance!

Alex

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# Homework Help: Physics question - 2D movement please help!

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