Answer:
Zero
Explanation:
Average velocity is given by:

where
d is the displacement of the trip
t is the time it takes for the trip to complete
In this problem, the net displacement of the swimmer is zero. In fact:
- First, he swims 30.0 m in the north direction
- Then, he travels back (-30.0 m) in the south direction, to the starting position
Since the final position is equal to the starting position, the displacement is zero:
d = 0
And therefore, the average velocity is also zero.
Using the idea of motion under gravity, it will take 0.5 seconds more before the phone hits the ground.
<h3>What is the distance covered?</h3>
The distance covered is obtained form the equations of kinematics under gravity.
Now;
v = u + gt
Recall that it was dropped from a height hence u = 0 m/s
v = gt
v = 9.8 m/s^2 * 4 s
v = 39.2 m/s
Now;
h = ut + 1/2gt^2
but u = 0 m/s
h = 1/2gt^2
h = 1/2 * 9.8 * (4)^2
h = 78.4 m
The phone will not hit the ground within this time
For the phone to hit the ground;
h = 1/2gt^2
if h = 100 m
100 = 1/2 * 9.8 * t^2
2 * 100/9.8 = t^2
t = √2 * 100/9.8
t = 4.5 seconds
It will take about 0.5 seconds more before the phone will hit the ground.
Learn more about motion under gravity:brainly.com/question/15120445
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