Posted by **Jery** on Tuesday, April 20, 2010 at 1:32am.

If a ball is thrown vertically upward from the roof of 32 foot building with a velocity of 112 ft/sec, its height after t seconds is s(t)=32+112t–16t2 . What is the maximum height the ball reaches?What is the velocity of the ball when it hits the ground (height 0 )?

- Calculus -
**Reiny**, Tuesday, April 20, 2010 at 7:39am
v(t) = s'(t) = 112 - 32t

at max v = 0

32t = 112

t = 3.5

then s(3.5) = ......

when it hits the ground, s(t) = 0

16t^2 - 112t - 32 = 0

t^2 - 7t - 2 = 0

solve using the quadratic formula,

sub the positive answer into v(t)

- Calculus -
**Kelly**, Tuesday, April 20, 2010 at 7:37pm
Hi I have the same question. The first part is correct to find the maximum height, but while solving for the quadratic formula to find the velocity when it hits the ground, the answer is incorrect. (You would get 7.2749 and -0.27492 after solving the quadratic)

- Calculus -
**Kelly**, Tuesday, April 20, 2010 at 7:41pm
Nevermind! I figured out you're supposed the plug the positive value into the derivative v'(t).

## Answer this Question

## Related Questions

- Math Calc - If a ball is thrown vertically upward from the roof of 48 foot ...
- Calculus Help - If a ball is thrown vertically upward from the roof of 64 foot ...
- calculus - If a ball is thrown vertically upward from the roof of 64 foot ...
- Calc - If a ball is thrown vertically upward from the roof of 48 foot building ...
- calculas - If a ball is thrown vertically upward from the roof of 48 foot ...
- math - If a ball is thrown vertically upward from the roof of 32 foot building ...
- Math - If a ball is thrown vertically upward from the roof of 48 foot building ...
- math - A person standing on the roof of a building throws a ball directly upward...
- Math - With s(t) measured in feet and t in seconds, the equation s(t)= -16t^2...
- College Algebra - A ball is thrown up from a twelve foot platform with an ...

More Related Questions