SOLUTION: {{{h(t)=-16t^2+64t+90}}} please help me find The max height Please The total time the ball is in the air The vertex would be nice to

Algebra ->  Coordinate-system -> SOLUTION: {{{h(t)=-16t^2+64t+90}}} please help me find The max height Please The total time the ball is in the air The vertex would be nice to      Log On


   



Question 1029055: h%28t%29=-16t%5E2%2B64t%2B90 please help me find
The max height Please
The total time the ball is in the air
The vertex would be nice to

Found 3 solutions by Boreal, Natolino1983, solver91311:
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
The vertex is the maximum height.
The t value is -b/2a and that is -(64/-32) or 2 seconds.
At t=2, h(t)=-64+128+90=154 feet.
Set the equation equal to 0 to find the total time the ball is in the air.
-16t^2+64t+90=0
quadratic formula
(-1/32)(-64+/- sqrt (4096+5760); sqrt (9856)=99.277)
One root is negative, which would be the left end of the parabola. The other is positive, and that is (-1/32)*(-163.277)=5.102 seconds. Notice that at x=0, y=90, the 90 is the height at which the ball was thrown. Also, the 64 represents the velocity in feet/second that the ball was thrown. Gravity is pulling back at 32 feet/sec^2, and 64/32 or 2 seconds will be the maximum height.
graph%28300%2C200%2C-5%2C5%2C-10%2C200%2C-16x%5E2%2B64x%2B90%29

Answer by Natolino1983(23) About Me  (Show Source):
You can put this solution on YOUR website!
This is quite simple.
H(t) = -16t^2 + 64t + 90 =-16(t^2-4t-45/8)= -16((t-2)^2 -77/8) = 154 -16(t-2)^2.
So Max Height = 154 (when t=2).
Total Time in air, can be obtain with H(t) =0, (t-2)^2 =154/16, with t>2, t=5,1 (s).
Vertex is (154,2)

Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!

The time that the ball reaches maximum height is the abscissa of the vertex. The abscissa of the vertex for any parabola represented by a function of the form +f%28x%29+=+ax%5E2+%2B+bx+%2B+c is given by -b%2F2a. The maximum height is represented by the ordinate of the vertex.

So, evaluate -64%2F2%28-16%29 to find the time in seconds when the projectile will be at the vertex. Then evaluate the function at this value of t to find the height at that time.

You cannot solve for the total time of flight with the information given. You must specify the height at which the projectile comes to rest. If it comes to rest on the ground, then this value is zero, but in general, would be h%5Bf%5D Once you decide what this value is, you can solve the quadratic equation:

-16t%5E2+%2B+64t+%2B+90+=+h%5Bf%5D%5D

Discard the smaller valued root.

John
My calculator said it, I believe it, that settles it