algebra

[pboland]

I am having a heck of time with these problems, anyone please help.
If an object is thrown upwar, its height 'h' at time 't' is given by the equation
h(t)=-16t^2+Vot+ho
where vo+initial velocity
ho=initial height.
Suppose you drop your decaf soy chai from the roller coaster at Cedar Point, when you are at its highest point, which is 420 feet above ground.
A. What is the initial height of the chai? 420
B. What is its initial velocity?
C. Write the equation for the height at time 't'.
h(t)=-16t^2+420
D. How long does it take the chai to reach the ground? I know that I am trying to find 0, but I am having a difficult time with the formula.

 

[tkhunny]

A. What is the initial height of the chai? 420

Close: 420 ft

B. What is its initial velocity?

No answer? You do show it in C. 0 ft/sec Good.

C. Write the equation for the height at time 't'.

h(t)=-16t^2+420

D. How long does it take the chai to reach the ground?
I know that I am trying to find 0, but I am having a difficult time with the formula.

What do you mean "trying to find 0"?
Solve h(t) = 0 or -16t^2 + 420 = 0.

For t > 0
-16t^2 + 420 = 0
420 = 16t^2
t^2 = 420/16 = 210/8 = 105/4
t = ½*sqrt(105) = 5.1234 sec

 

[pboland]

Algebra

I do not understand your answer to B.

 

[stapel]

Re: Algebra

I do not understand your answer to B.

The tutor means that you didn't list your answer to part (B), but included the answer, implicitly, in what you posted for part (C).

Eliz.