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a ball is thrown straight up at an initial velocity of 54 feet per second, the height of the ball at T seconds after it is thrown is given by the formula h(t)=5t-12t^2, how many seconds after the ball is thrown will it return to the ground

 Dec 14, 2015

Best Answer 

 #4
avatar
+5

Why does it matter? It's gonna hit the ground eventually anyway.

 Dec 14, 2015
 #1
avatar+8581 
0

hhhmmm..

 Dec 14, 2015
 #2
avatar+33661 
+5

Hmm!   If u is the initial upward velocity and g is the gravitational acceleration,  then

 

\(\frac{dh}{dt}= u-g\times t\)

 

This means that

 

\(h(t)=u\times t-\frac{g}{2}\times t^2\)

 

So, either u is 54 or the initial velocity is 5 ft/sec.  Which is it?

 

(Also, it looks like g = 24 ft/sec^2 here.)

 Dec 14, 2015
 #3
avatar+8581 
0

Thanks! I didnt know how to do it.. :(

 Dec 14, 2015
 #4
avatar
+5
Best Answer

Why does it matter? It's gonna hit the ground eventually anyway.

Guest Dec 14, 2015
 #5
avatar+1316 
0

I did this and got 4.5f/1s^2

I also find out the ball goes to 60 feet high before it start coming back

 

If Alan not say the gravity is 24f/s^2 I probably not notice.

 

So know I wonder why this is not 32f/s^2. I think maybe the ball have a low terminal velocity. To find out that we have to know the drag coefficient and the mass of the ball. I not really know how to do it for this. 

 

Alan can a drag coefficient make it seem like the gravity is weaker?

 Dec 16, 2015
 #6
avatar+1316 
0

I not answer this right. It take 4.5 seconds to hit the ground is what I mean.

 Dec 16, 2015

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