A rock climber is scaling rock wall at 10 m above the ground, and is moving downward at a speed of 0.25 m/s. If their phone falls out of their back pocket, how long before it shatters onto the ground?

The time taken before the phone hits the ground is 1.4 s.

Explanation:

Given;

height of the rock wall, h = 10 m

speed of the climber, v = 0.25 m/s

The time taken before the phone hits the ground is given;

h = ut + ¹/₂gt²

10 = 0.25t + ¹/₂(9.8)t²

20 = 0.5t + 9.8t²

9.8t² + 0.5t - 20 = 0

solving this quadratic equation;

t = 1.4 s

Therefore, the time taken before the phone hits the ground is 1.4 s.

frequency or wavelenth of em radiation in a vacuum

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.