Question

Mark is in a deep hole looking for treasure. He is standing 8 feet below the surface. He throws an old coin he found with an initial upward velocity of 22 ft/sec. How long until it lands outside the hole, having gone up and come back down? Use the formula where h is the height of the coin in feet (relative to the surface) and t is the time in seconds since Mark threw it. Ignore air resistance and round your answer to the nearest tenth.

Answer 1

Option D is correct.

Explanation:

We have been given a function:

`0=-16t^2+22t-8`

We will find at h=0 to find the time it will take until it lands outside the hole, having gone up and come back down.

In the given function we will put h=0.

`-16t^2+22t-8=0`

On solving the above equation we will get t

`t=(1)/(16)(11-i√(7))\text{and}{(1)/(16)(11+i√(7))`

So, it will never happen we are getting time as imaginary value.

Hence, it will not make it outside the hole.

Therefore, option D is correct.