A juggler is performing her act using several balls. She throws the balls up at an initial height of 4 feet, with a speed of 15 feet per second. If the juggler doesn't catch one of the balls, about how long does it take the ball to hit the floor?

Hint: Use H(t) = −16t2 + vt + s.

7.52 seconds
1.15 seconds
0.47 second
0.22 second

Question

A juggler is performing her act using several balls. She throws the balls up at an initial height of 4 feet, with a speed of 15 feet per second. If the juggler doesn't catch one of the balls, about how long does it take the ball to hit the floor?

Hint: Use H(t) = −16t2 + vt + s.

 7.52 seconds
 1.15 seconds
 0.47 second
 0.22 second

anonymous · Answer

$$H(t)=-16t^2+15t+4$$ set 
$$-16t^2+15t+4=0$$ and solve for $t$

anonymous · Answer

on account of when it hits the floor, the height is zero

anonymous · Answer

you can solve by a) using the quadratic formula or b) cheating i prefer cheating http://www.wolframalpha.com/input/?i=-16t^2%2B15t%2B4%3D0

anonymous · Answer

actually it is NOT D

anonymous · Answer

beware of answers with no explanation
they are often wrong and you have no way of knowing

lalaland_lauren · Answer

Yeah I've learned my lesson from those :P I enjoy option b and wolframalpha as well :)

anonymous · Answer

lol yeah B

lalaland_lauren · Answer

That's what I was just about to say, it took me a while but I noticed it's close to 1.2 and the only answer close to that was 1.15

lalaland_lauren · Answer

Funny how we chose option b and the answer ended up being b xD

lalaland_lauren · Answer

I'm confused by that...

anonymous · Answer

my bad i thought this was physics