SOLUTION: The Height in feet of a baseball above ground is given by h(t)=-16t^2+32t+3 where t represents the time in seconds after the baseball is thrown. If you throw the ball into the a

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equation Customizable Word Problems -> SOLUTION: The Height in feet of a baseball above ground is given by h(t)=-16t^2+32t+3 where t represents the time in seconds after the baseball is thrown. If you throw the ball into the a      Log On


   



Question 111036: The Height in feet of a baseball above ground is given by h(t)=-16t^2+32t+3 where t represents the time in seconds after the baseball is thrown.
If you throw the ball into the air, how many seconds have passed until the ball hits the ground??

I really don't understand how to put this problem in the equations it's supposed to go into and I don't understand how to solve them...help!

Found 2 solutions by scott8148, ankor@dixie-net.com:
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
when the ball hits the ground, the height (h(t)) is zero ___ so 0=-16t^2+32t+3

solve for t using the quadratic formula (the answer is between 2 and 3 seconds)

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
The Height in feet of a baseball above ground is given by h(t)=-16t^2+32t+3 where t represents the time in seconds after the baseball is thrown.
If you throw the ball into the air, how many seconds have passed until the ball hits the ground??
:
Look at the three elements of the equation:
-16t^2 is the force of gravity, negative because it is pulling it down
:
+32t is the speed of the ball upward when it is thrown
:
+3 is the point above the ground that the ball thrown
:
t is in seconds
:
h = height in feet
:
When the ball hits the ground the height is 0, so we have:
;
-16t^2 + 32t + 3 = 0
:
Use the quadratic formula to find t; a = -16; b = 32; c = 3
t+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
:
t+=+%28-32+%2B-+sqrt%28+32%5E2+-+4%2A+-16+%2A+3+%29%29%2F%282%2A-16%29+
:
t+=+%28-32+%2B-+sqrt%281024+-+%28-192%29+%29%29%2F%28-32%29+
:
t+=+%28-32+%2B-+sqrt%281024+%2B+192+%29%29%2F%28-32%29+
:
t+=+%28-32+%2B-+sqrt%281216+%29%29%2F%28-32%29+
:
t+=+%28-32+-+34.87%29%2F%28-32%29+; we only want this solution
:
t+=+%28-66.87%29%2F%28-32%29+
:
t = +2.089 sec, when it hits the ground
:
A graph would look like this. Vertical = height; horizontal = time in sec
+graph%28+300%2C+200%2C+-2%2C+4%2C+-10%2C+25%2C+-16x%5E2%2B32x%2B3%29+
:
Note that it crosses the y axis at 3' when t = 0 and max height is about 19 ft at 1 sec
;
Did this help you understand this?