1. olivia is taking pictures of the ocean at the edge of the cliff when she accidently drops her phone. the phone hit the water at a vertical
velocity of 15.75m/s and landed 16m away from the base of the cliff.
a. how tall is the cliff?
b. how long did it take for the phone to hit the water?
c. what was the phone's horizontal velocity?

Answers:

a) 12.54 m

b) 1.6 s

c) 0 m/s

Explanation:

This problem can be solved with the following equations:

(1)

(2)

Where:

is the phone's final height

is the phone's intial height and the cliff's height

is the initial velocite, since the phone was dropped

is the time it took to the phone to hit the water

is the acceleration due gravity, always directed downwards

is the angle with the horizontal

is the phone's final velocity, directed downwards

a) Let's begin by rewriting (1) and (2) acording to the information given above:

(3)

(4)

Isolating from (4) and substituting in (3):

(5)

(6)

(7) This is the height of the cliff

b) Finding from (4):

(8)

(9)

(10)

c) Since the horizontal velocity is:

the doppler effect is used by weather forecasters to measure 

moving clouds