Thread: time for ball to hit the ground

I've tried this problem 4 times now and i keep getting the wrong answer. I thought it would be a simple quadratic equation problem but I'm just not getting it.


A baseball is “popped” straight up by a batter. The height of the ball above the ground is given by the function , where t is time in seconds after the ball leaves the bat and y is the height of the ball in feet.

It wants me to find at what time the ball hits the ground.

Originally Posted by xacsempire

I've tried this problem 4 times now and i keep getting the wrong answer. I thought it would be a simple quadratic equation problem but I'm just not getting it.


A baseball is “popped” straight up by a batter. The height of the ball above the ground is given by the function , where t is time in seconds after the ball leaves the bat and y is the height of the ball in feet.

It wants me to find at what time the ball hits the ground.

Hi xacsempire,

I don't know if anyone else can see it, but I cannot see your function. Can you just type it out?

The function is y=f(t)= -5t^2+40t+4

heres what the graph looked like.

Originally Posted by xacsempire

The function is y=f(t)= -5t^2+40t+4

heres what the graph looked like.

Then the ball "hits the ground" when y= 0. Solve -5t^2+ 40t+ 4= 0 by factoring, or completing the square, or using the quadratic formula.