A shell is fired from a long-range gun with an initial velocity = 300 m/s at 30 degrees on a flat surface. Find the height of the projectile at t=20s. Answer key says 1000 m, can't get the right answer!

Question

anonymous · Answer

I tried change in x = V0(t) +1/2(a)(t^2)

x=300(20) + 1/2(-10)(20^2) = 4000 m, but doesn't match up to 1000m

(We use 10 as a simplified g)

wolfe8 · Answer

The bullet was shot at an angle, so you will have to resolve the velocity into x and y components.

wolfe8 · Answer

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anonymous · Answer

So Vx = 300cos30, Vy = 300sin30

anonymous · Answer

I was trying to find formulas with t so I can substitute it in

wolfe8 · Answer

Yup. So use the formula for range. I can't remember which one it is sorry. I'm exhausted.

anonymous · Answer

Ah ok. Will try. Thanks and gl on ur exam!

anonymous · Answer

Does anyone know the right formula? I'm confused which one to use and how to set it up

anonymous · Answer

Got it, it is Y = $$Vyi (t) - 1/2 (g)(t^2) = 300\sin30(2) - 1/2 (10)(20^2)$$
= 3000-2000 = 1000m , using g = 10