I'm still doing grade 12 physics, so my physics knowledge is VERY limited.(adsbygoogle = window.adsbygoogle || []).push({});

So I have a question about proving that a projectile launched 45 degrees above horizontal gives the greatest horizontal displacement.

I have to ideas to go about proving this:

1. Subbing Equations

I have currently made 2 equations that I can think of:

Vertical Component: 0=V[tex]_{}y1[/tex]-4.9t[tex]^{}2[/tex]

Horizontal Component: t=d[tex]_{}x[/tex]/V[tex]_{}x1[/tex]

I subbed equation 2 into equation 1. However, I got stuck at 0=V[tex]_{}y1[/tex]V[tex]_{}1x[/tex]-4.9d[tex]_{}x[/tex]

Where's the third equation?

2. Finding the horizontal displacement of 44 degrees and 46 degrees, and compare their expected lower horizontal displacement to that of 45 degrees. Or basically just find the time the projectile is moving, just solving for t when vertical displacement is 0.

Considering my grade level, is solution 1 possible, or should I use solution 2?

Thanks!

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# Homework Help: Proving 45 degrees is optimal value for greatest horizontal range

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