A skydiver drops her watch as she jumps out of a plane flying at an altitude of 6,400 feet. If the equation for height as a function of time is h(t)=-16t^2+initial height where t is time in seconds and h(t) is height in feet, how many seconds will it take for the watch to hit the ground?

To hit the ground, it will take the watch:

Step-by-step explanation:

Making use of the provided equation:

Which can be modified specifically for this case:

Time must be replaced a certain number of times until the value is zero, this can be done one by one, but since it would be too many iterations I will show you some examples and what you could deduce in each case.

With t = 1 second:

With t = 7 seconds:

With h = 15 seconds:

With h = 21 seconds:

With h = 20 seconds:

Since with 20 seconds the exact value of zero is obtained, this time is the exact time it would take the watch to fall to the ground, since when this time is reached the height (h) will be zero, that is, at ground level .

the answer is c

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