Question

A rifle is fired up at an angle of 5.5 degrees above horizontal. If the inital velocity of the bullet is 570/s, what will be it's velocity 2.5s after firing?

Answer 1

Answer on question #64394, Physics / Mechanics | Relativity

Question A rifle is fired up at an angle of 5.5 degrees above horizontal. If the inital velocity of the bullet is 570 m/s, what will be it’s velocity 2.5s after firing?

Solution The horizontal initial velocity is

$v_{h}=v\cdot\cos\alpha=570\cdot\cos 5.5{}^{\circ}\approx 567.4\,m/s$

The vertical initial velocity is

$v_{v}=v\cdot\sin\alpha=570\cdot\sin 5.5{}^{\circ}\approx 54.6\,m/s$

The horizontal velocity will not change. The verical on will change in the following way due to gravity:

$v_{2v}=v_{v}-gt^{2}/2=54.6-9.8\cdot 2.5^{2}/2\approx 24\,m/s$

So, final velocity after 2.5 seconds will be

$v_{f}=\sqrt{v_{h}^{2}+v_{2v}^{2}}=\sqrt{567.4^{2}+24^{2}}\approx 567.9\,m/s$

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