If someone throws a ball down from a height of 100 meters, the ball's distance from the ground can be modeled by the equation: d = − 9.8 t 2 − 15 t + 100 where t is the time in seconds and d is the distance in meters. At what time (t) will the ball hit the ground? (Hint: what does this mean for d=distance?) You will get two answers. Do both make sense? (Explain in detail Why or Why not

The ball will hit the ground when t = 2.52s. The other answer, which is t = -4.05s, does not make sense, because the answer is an instant of time, and there are no negative time measures.

Step-by-step explanation:

To solve this question, we have to find the roots of a quadratic equations, which is explained next.

Given a second order polynomial expressed by the following equation:

.

This polynomial has roots such that , given by the following formulas:

In this problem, we have that:

Ball's distance from the ground.

So

At what time (t) will the ball hit the ground?

This is t when . So

The ball will hit the ground when t = 2.52s. The other answer, which is t = -4.05s, does not make sense, because the answer is an instant of time, and there are no negative time measures.

40 minutes

step-by-step explanation:

add the time and multiply by 2