A wave travels through a medium because

The correct term is accretion disk. This refers to a formation, typically a circumstellar disk, created by dispersed matter revolving around a large central body, which is usually a star. The gravitational pull causes the material in the disk to spiral inward towards the center.

The total duration from the stone's drop to the echo being heard is 8.9 seconds. The sound takes 0.9 seconds to reach the listener, meaning it takes the stone 8 seconds to descend to the well's bottom. Using gravitational acceleration, the well's depth calculates to be approximately 313.6 meters.

This initial stage represents a right triangle. If the aircraft is positioned 400 km to the east and 300 km to the south of the origin while traveling in a straight path, you can form a right triangle with sides measuring 300, 400, and c. You might notice that these dimensions correspond to multiples of the Pythagorean triple 3, 4, 5, meaning that the length of c is 500 km. Alternatively, you would indicate
.

For the second step, assuming I am correctly understanding "degrees south of east," it involves calculating the angle between the horizontal line indicating east and the trajectory of the aircraft. I created a diagram illustrating this (see attached). You could employ a trigonometric function related to one of the angles to find the solution. I selected
. Therefore, I deduce that the angle is 37° south of east.

Ethylene glycol is known as the main component found in antifreeze.
The molecular formula for ethylene glycol is C₂H₆O₂.
Its molar mass is calculated as C₂H₆O₂ = (2×12) +(6×1) + (216) = 62g/mol
Given that antifreeze comprises 50% by weight, there exists 1 kg of ethylene glycol mixed with 1 kg of water.
ΔTf = Kf×m
ΔTf refers to the change in the freezing point.
= starting temperature of water - freezing temperature of the solution
= 0°C - Tf
= -Tf
Kf stands for the freezing point depression constant of water, which is 1.86°C/m
m is the molarity of the solution.
=(mass/molar mass) where mass of solvent is in kg
=1000g/62 (g/mol) /1kg
=16.13m
Substituting the value into the equation gives us
-Tf = 1.86 × 16.13 = 30
thus Tf = -30°C

Utilizing the equation F = ma, where F represents the force applied by the machine, A denotes acceleration (equivalent to v/t, with v as velocity and t as time), and M symbolizes mass, we can calculate as follows: F = mv/t. Thus, F = (0.15kg) (30 – 0 m/s) / 0.5 s, resulting in F = 9 N.