Answer
2.8 s
Work Step by Step
We are asked to solve when a ball hits the ground if its motion is governed by the equation:
$$ -16t^2-20t+180$$
$$x= \frac{-b \pm \sqrt{b^2-4ac}}{2a}$$
Where b is the coefficient of the term with a variable raised to the first power, a is the coefficient of the squared term, and c is the coefficient of the term without a variable in front of it.
When we plug the given values, we consider only the positive value to get:
2.8 s
