Question

2. Your phone slips from your pocket as you’re going up a ladder of a high building.

Your phone falls for 2.7 seconds before you heart it hit the cement below.

a. At what height did the phone fall from? (Hint: Your phone’s initial velocity is

zero.)

b. What was the velocity of your phone when it hit the cement?

Answer 1

a. The height can be determined from the kinematic formula:

$$h = \dfrac{gt^2}{2}$$

where $t = 2.7s$ and $g = 9.8m/s^2$ is the gravitational acceleration.

Thus, obtain:

$$h = \dfrac{9.8\cdot 2.7^2}{2} \approx 36m$$

b. The velocity can be found using the definition of acceleration:

$$v = gt = 9.8\cdot 2.7\approx 26m/s$$

Answer. a)36m, b)26m/s.