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Projectile Motion Questions, Please help!

  • Thread starter heeling23
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  • #1
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1. A ball is thrown horizontally from a height of 22 m and hits the ground with a speed that is three times its initial speed. What was the initial speed?

2. A projectile is fired with initial speed v at an angle 30° above the horizontal from a height of 41 m above the ground. The projectile strikes the ground with a speed of 1.4v. Find v.

These are essentially the same problems right? Except for the fact that #2 has a vertical initial velocity. I tried using V^2=Vo^2+2ah but I got the answer wrong. Then I tried finding the time for the first one using y=1/2at^2 and then using v=vo+at and I got the wrong answer again.

Any help is appreciated!
Thanks,
heeling23
 

Answers and Replies

  • #2
Doc Al
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heeling23 said:
I tried using V^2=Vo^2+2ah but I got the answer wrong. Then I tried finding the time for the first one using y=1/2at^2 and then using v=vo+at and I got the wrong answer again.
Either approach, done correctly, would work. Post the details of what you did for more help. (Hint: Only the vertical component of motion is accelerated.)
 

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