Question

While hiking, Julia kicked a small rock off a ledge that was meters above a crevasse. Use GeoGebra to graph the situation using the formula y=−4.9t2+9
. Use the graph to determine when the rock will hit the bottom of the crevasse, 2 meters below ground level. Round your answer to the nearest tenth of a second.(1 point)
The rock will hit the bottom of the crevasse in
seconds.

Answer 1

Set y = −2 (2 m below ground): −4.9t^2 + 9 = −2
⇒ −4.9t^2 + 11 = 0 ⇒ 4.9t^2 = 11 ⇒ t = sqrt(11/4.9) ≈ 1.498 s.

Rounded to the nearest tenth: 1.5 seconds.