A ball is kicked upward with an initial velocity of 56 feet per second. The ball's height h (in feet) can be expressed as a function of time t (in seconds) by the equation h = -16t2 + 56t. How much time does the ball take to return to the ground?
A)
1.75 seconds
B)
2.50 seconds
C)
2.75 seconds
D)
3.50 seconds

Question

A ball is kicked upward with an initial velocity of 56 feet per second. The ball's height h (in feet) can be expressed as a function of time t (in seconds) by the equation h = -16t2 + 56t. How much time does the ball take to return to the ground?
A)
1.75 seconds
B)
2.50 seconds
C)
2.75 seconds
D)
3.50 seconds

anonymous · Answer

solve the quadratic 0 = -16t^2 + 56t

accessdenied · Answer

h(t) tells you the height.  It reaches the ground when height is 0, which is just sensible by the meaning of the function.
h(t) = 0   <==>  -16t^2 + 56t = 0
The initial solution is at t= 0,  so we just need the other solution to the quadratic.

anonymous · Answer

Alright thanks