[9.06]A batter hits a baseball upward with an initial speed of 96 feet per second. After how many seconds does the ball hit the ground? Use the formula h = rt − 16t2 where h represents height in feet and r represents the initial speed.

Question

shane_b · Answer

You just need to solve the quadratic noting that the height will be 0 when the ball hits the ground:
$$h=0m=rt-16t^2=(96m/s)(t)-16t^2$$This will result in two values but since time can only be positive, that's the correct answer.

anonymous · Answer

im still confused...

shane_b · Answer

What are you confused about?

anonymous · Answer

96t-16t^2 ?

shane_b · Answer

Ok.  The question tells you the initial speed is 96m/s and that r represents that value.  All I did was plug in 96m/s for r in the equation they gave you.

shane_b · Answer

Ultimately the only thing you need to do is solve for t in the equation:$$-16t^2+96t=0$$

anonymous · Answer

oh okay thank you

shane_b · Answer

Just so you can check your answer, you should get 6 seconds.

anonymous · Answer

yes thats what i was just about to ask :)