1) True 2) True 3)True I hope I helped
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:


"The rock has a downward acceleration of 9.8 m/s2" is the one among the following choices that explains the <span>rock’s acceleration at the instant that it reaches the top of its trajectory (where its velocity is momentarily zero). The correct option among all the options that are given in the question is option "D". </span>
In the veeeery distant future, our sun will transform into a red giant, and in the even more distant future, it will become a white dwarf.