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Hot air rises = it's less dense than cold air = falls
The best and most correct answer among the choices provided by the question is the second choice. The rope will not be broken until the net force acting on it is not equal to zero anymore. I hope my answer has come to your help. God bless and have a nice day ahead!
Answer:
<em>The total time is: t=451.22 sec</em>
<em>The average speed is: V=34.57 m/s</em>
Explanation:
<u>Average speed</u>
The average speed is calculated by dividing the total distance traveled by an object (x) by the total time it took it to travel that distance (t).

Since the student makes the trip in two parts, we have to calculate the total distance and the total time.
We know the distance to school is 7.8 Km = 7,800 m. The student makes his way home over the same distance, thus the total distance is
x=2*7,800 m=15,600 m
The first trip to school was done at an average speed of v1=32.6 m/s. Knowing the distance and speed, we can calculate the time:

The second trip back home was done at an average speed of v2=36.8 m/s. Let's calculate the second time:

The total time is:


The average speed is:


Answer:
12.974 m/s
Explanation:
t = Time taken
u = Initial velocity
v = Final velocity
s = Displacement
g = Acceleration due to gravity = 9.81 m/s²
= Coefficient of friction =0.66
a = Acceleration = 

Car's original speed before braking was 12.974 m/s