A ball is thrown from a height of 44 meters with an initial downward velocity of 6 m/s. The ball's height h (in meters) after t seconds is given by the following.

H=44-6t-5t^2
How long after the ball is thrown does it hit the ground?
Round your answer(s) to the nearest hundredth.
(If there is more than one answer, use the "or" button.)

1 answer

To find out when the ball hits the ground, we need to determine when the height \( h(t) = 0 \). The height of the ball is given by the equation:

\[ h(t) = 44 - 6t - 5t^2 \]

Setting this equal to zero to find when the ball hits the ground:

\[ 44 - 6t - 5t^2 = 0 \]

Rearranging the equation gives us:

\[ -5t^2 - 6t + 44 = 0 \]

Multiplying the entire equation by -1 to make the leading coefficient positive:

\[ 5t^2 + 6t - 44 = 0 \]

Now we will use the quadratic formula to solve for \( t \):

\[ t = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \]

In this case, \( a = 5 \), \( b = 6 \), and \( c = -44 \). We first calculate the discriminant:

\[ b^2 - 4ac = 6^2 - 4 \cdot 5 \cdot (-44) = 36 + 880 = 916 \]

Now using the quadratic formula:

\[ t = \frac{-6 \pm \sqrt{916}}{2 \cdot 5} \]

Calculating \( \sqrt{916} \):

\[ \sqrt{916} \approx 30.233 \]

Now substituting back into the formula:

\[ t = \frac{-6 \pm 30.233}{10} \]

Calculating the two possible values for \( t \):

  1. Using the plus sign:

\[ t = \frac{-6 + 30.233}{10} = \frac{24.233}{10} \approx 2.4233 \]

  1. Using the minus sign:

\[ t = \frac{-6 - 30.233}{10} = \frac{-36.233}{10} \approx -3.6233 \quad (\text{not physically meaningful, as time cannot be negative}) \]

Thus, the time when the ball hits the ground is:

\[ t \approx 2.42 \text{ seconds (rounded to the nearest hundredth)} \]

The answer is:

2.42 seconds.