Answer:
D
Explanation:
this is simple, because when air is removed, means that there is no particles in the jar so vacuum is achieved, and when you can't hear a sound means that the sound couldn't travel through the vacuum. which means that sound cannot travel through vacuum,
as a result, sound requires a medium ( air) travel from one point to another.
hope it helps, if not please report it so that someone else gets to try it
Answer:
Vertical Height = 0.784 meter, Speed back at starting point = 10 m/s
Explanation:
Given Data:
V is the overall velocity vector,
and
are its initial vertical and horizontal components

To find:
Max Height
achieved
Calculation:
1) Using the
equation of motion, we know

2) In terms of gravity
height
and the vertical component of Velocity
.
3) As
as at maximum height the vertical component of velocity is zero maximum height achieved

putting values
4) 
5) As for the speed when it reaches back its starting point, it will have a speed similar to its launching speed, the reason being the absence of air friction (Air drag)
The first: alright, first: you draw the person in the elevator, then draw a red arrow, pointing downwards, beginning from his center of mass. This arrow is representing the gravitational force, Fg.
You can always calculate this right away, if you know his mass, by multiplying his weight in kg by the gravitational constant

let's do it for this case:

the unit of your fg will be in Newton [N]
so, first step solved, Fg is 637.65N
Fg is a field force by the way, and at the same time, the elevator is pushing up on him with 637.65N, so you draw another arrow pointing upwards, ending at the tip of the downwards arrow.
now let's calculate the force of the elevator

so you draw another arrow which is pointing downwards on him, because the elevator is accelating him upwards, making him heavier
the elevator force in this case is a contact force, because it only comes to existence while the two are touching, while Fg is the same everywhere
According to the second law of thermodynamics,
the answer is
<span>4. The entropy of the universe is increasing. </span>
<span>vf^2 = vi^2 + 2*a*d
---
vf = velocity final
vi = velocity initial
a = acceleration
d = distance
---
since the airplane is decelerating to zero, vf = 0
---
0 = 55*55 + 2*(-2.5)*d
d = (-55*55)/(2*(-2.5))
d = 605 meters
</span>