Question

30 POINTS!
Leyla drops a penny from a height of 150 m.

How long will it take the penny to hit the ground?

Use the formula h(t)=−4.9t^2+vot+h , where vo is the initial velocity and h is the initial height.

Round to the nearest tenth of a second.
Enter your answer in the box. Show your work.

Answer 1

Answer: 5.5 seconds

Since the penny is dropped and not thrown, the initial velocity is 0 and the initial height is given as 150m. Plugging these into the given equation result in $-4.9t^2+0t+150=-4.9t^2+150$. To find how long it will take for the penny to hit the ground we set the equation equal to zero and solve for t. Since this doesn't factor, you'll need to use the quadratic formula:

$+/-\frac{\sqrt{0^2-4(-49)(150)}}{2(-49)} =+/-\frac{10\sqrt{15} }{7}=+/-5.533$. Since time cannot be negative, the answer will be the positive 5.5 seconds.