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Nov 28 2017 07:38pm
Must be solved with a clear explanation in the next 30 minutes



This post was edited by Logarius on Nov 28 2017 07:44pm
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Nov 28 2017 07:44pm
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Nov 28 2017 08:08pm
Quote (Logarius @ Nov 28 2017 08:38pm)
Must be solved with a clear explanation in the next 30 minutes

https://i.imgur.com/BIGTbbm.jpg


a) y(t) = 120ft/sec(sin30t)-16t^2 + 5.5 ft = 0
120(sin30)-16t^2 = -5.5
60-16t^2=-5.5
-16t^2=-65.5 (multiply each side by -1)
16t^2=65.5
t^2=65.5/16
square root(t^2)=square root(65.5/16)
t=2.02 seconds

x(2.02) =120(cos30)x2.02 seconds = 103.92 feetx2.02 = answer = 209.92 feet

Good luck with rest. I'm also not 100 percent certain I'm correct.

b and c should be 45 degree angles. But not sure on proof or expressions since it's been a while.

This post was edited by WXdisaster on Nov 28 2017 08:19pm
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Nov 28 2017 08:43pm
That's not right for part a. The time is outside of the sin(30), you put it inside in the first step, and dropped the t factor on the velocity portion completely in the second step.

You should end up with a quadratic formula 0 = 120*sin(30)*t - 16*t^2 + 5.5. You can solve this with the quadratic equation and get t = -0.089 or t = 3.84. Obviously time can't be negative so that root does not make sense in a practical application, so t = 3.84s
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Nov 28 2017 08:52pm
Quote (RageATM0998 @ Nov 28 2017 09:43pm)
That's not right for part a. The time is outside of the sin(30), you put it inside in the first step, and dropped the t factor on the velocity portion completely in the second step.

You should end up with a quadratic formula 0 = 120*sin(30)*t - 16*t^2 + 5.5. You can solve this with the quadratic equation and get t = -0.089 or t = 3.84. Obviously time can't be negative so that root does not make sense in a practical application, so t = 3.84s


you're right. :D Oh well. Holy hell. Glad I'm not doing this shit anymore. And jsp won't let me edit. fml.

This post was edited by WXdisaster on Nov 28 2017 08:52pm
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