Question
1. Ms. Whitmell goes on a trip to the moon and jumps from a hill into a crater.Her height with respect to time is modeled by the equation h(t)=-4t^2+12t+7 where t is time in minutes and h(t) is height in metres. a. What is the height of the hill? b. How long is Ms Whitmell in the air? c. What is Ms Whitmell's maximum height and at what time does this happen?
Solution
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(181 Votes)
Frida
Master ยท Tutor for 5 years
Answer
### a. 7 meters### b. 3.5 minutes### c. Maximum height is 16 meters at 1.5 minutes.
Explanation
## Step 1: Finding the initial height### The height of the hill is the height at
. Substituting
into the equation
gives
.## Step 2: Finding the time in the air### Ms. Whitmell lands when
. We solve
for
. Using the quadratic formula,
, we get
. This gives two solutions:
and
. Since time cannot be negative, the time in the air is
minutes, or 3.5 minutes.## Step 3: Finding the maximum height and time### The maximum height occurs at the vertex of the parabola. The
-coordinate of the vertex is given by
minutes. Substituting
into the height equation:
meters.