a stone was thrown from the top of a cliff 60 metres above sea level. the height of the stone above sea level t seconds after it was released is given by H(t)=-5t^2+20t+60 meters.
a. Find the time taken for the stone to reach its maximum height.
b. what was the maximum height above sea level reached by the stone?
c. How long did it take before the stone struck the water?

Question

a stone was thrown from the top of a cliff 60 metres above sea level. the height of the stone above sea level t seconds after it was released is given by H(t)=-5t^2+20t+60 meters.
a. Find the time taken for the stone to reach its maximum height.
b. what was the maximum height above sea level reached by the stone?
c. How long did it take before the stone struck the water?

anonymous · Answer

Can u find H'(t)

anonymous · Answer

i dont know the question above only gives that information

anonymous · Answer

Ask in physics. :D

hartnn · Answer

is this question related to calculus ?
if, yes differentiate H(t) and tell me what u get?

anonymous · Answer

this question is found in the chapter Quadratic equations and function and is not physics related or calculus. it is a 10th grade high level math question.

anonymous · Answer

i dont know calculus yet

anonymous · Answer

You know limit?

hartnn · Answer

so take this:
maximum value of function ax^2+bx+c is -b/2a
now compare your function with this, find a,b,c and then ffind maximum

hartnn · Answer

here compare it with  at^2+bt+c
what values of a,b,c u got ?

hartnn · Answer

@Bhagyashree

anonymous · Answer

I already figured it out. Thanks everyone!!! I really appreciated your help!