Please help me out with this problem!

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lucky090

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Feb 10, 2012
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in the bottom of the 9th inning, the bases are loaded and the braves are down by three runs. chipper johns steps to the plate. twice he swings and misses. The crowd heads for the exits. the next pitch is a fast ball down the middle. he swings and makes perfect contact with the ball, sending it up at 45 degree towards the fence 400 ft away.

a.determine how fast he must hit the ball to land at the base of the fence, neglecting the air resistance.

b. Determine whether there was a better angle at which to hit the ball so that it could clear a 12 ft fence.

HINT: law of cosines should be used.

THANK YOU!:)
 
Hello, lucky090!

In the bottom of the 9th inning, the bases are loaded and the Braves are down by three runs.
Chipper Johns steps to the plate. twice he swings and misses. .The crowd heads for the exits.
The next pitch is a fast ball down the middle. . What does that mean?
.. What is the height of the ball when the bat makes contact?
He swings and makes perfect contact with the ball, sending it up at 45 degree towards the fence 400 ft away.

a. Determine how fast he must hit the ball to land at the base of the fence, neglecting the air resistance.

b. Determine whether there was a better angle at which to hit the ball so that it could clear a 12 ft fence.

HINT: Law of Cosines should be used. .What triangle are we working with?
Click to expand...
 
- we have to assume the initial height
- this question is really confusing, but I copied the text as it is.


Please help me out!

Thanks!
 
As far as I know, to solve this problem you need to use equations of motions of a projectile (under constant gravity).

I do not know why laws of cosines have been hinted here.....
 
Hello again, lucky090!

We have to assume the initial height.
Click to expand...

It would be simpler if the initial height were zero.
. . But then we'd be watching a golf tournament!
 
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