How to find minimum speed?

  • Thread starter Sneakatone
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  • #1
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in a baseball game the batter hits the ball and launches it upward at n angle of 52.0 degrees...\


I used V_x=Vocos(/theta)+a_xt to solve for V_x and got 31.6m/s which is wrong. what should I do.
 

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Answers and Replies

  • #2
tms
644
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You are mixing the ball and the fielder together. First solve for the ball, finding out where and when it lands, then figure out how the fielder can get there.
 
  • #3
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I used the same equation and had 2.3 s and had 19.56 m/s. is that process correct?
 
  • #4
haruspex
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I used the same equation and had 2.3 s and had 19.56 m/s. is that process correct?
I make it 2.47s. Pls show your working.
I can't do part b because I don't know the layout of a baseball pitch. In fact, I don't understand how you're supposed to know which direction the ball went.
I note also that the question makes no allowance for the height off the ground when the ball was struck.
 
  • #5
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so I do 38 meters/ 2.47 seconds= 15.38 m/s .?
 
  • #6
tms
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I make it 2.47s. Pls show your working.
I can't do part b because I don't know the layout of a baseball pitch.
It's called a field or a diamond. A pitch in baseball is the throw the pitcher makes at the batter.
In fact, I don't understand how you're supposed to know which direction the ball went.
I think we are to assume that ball goes straight at the center fielder.
I note also that the question makes no allowance for the height off the ground when the ball was struck.
I think we are to assume it is to be caught at the same height it was hit from.
 
  • #7
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I still dont understand what to do
 
  • #8
haruspex
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I still dont understand what to do
First, a correction. I don't get 2.47s for the flight time of the ball, I get 6.10s. Sneakatone, if you do not get that pls post your working. If/when you have the flight time right, find where the ball will land (as tms already instructed).
 
  • #9
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I did 0=38cos(52)+(9.8)t


45/6.1= 7.4 m/s
would that be correct?
 
  • #10
tms
644
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I did 0=38cos(52)+(9.8)t
Why did you do that? You seem to be mixing up the horizontal and vertical components, among other things. Try using symbols to set up your equations; it will be clearer what is going on and where you are going wrong. It is best to proceed systematically. Start by drawing a diagram showing the forces on the ball. Then write down the kinematic equation for the vertical direction, then solve it for the time taken to go up and down.
 
  • #11
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this is how i see it
 

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  • #12
tms
644
17
The ball does not keep going up without regard to gravity. What is the shape of the ball's trajectory?

And the distance the fielder is from the batter has no influence on the ball's trajectory.
 

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