Wavelength and speed both depend on the material of the medium.
Explanation:
Let denote the frequency of a wave. Let denote the speed of that wave in a given medium. Let denote the wavelength of that wave in this medium.
The frequency of a wave stays the same regardless of the material of the media. However, the speed of a wave indeed depends on the material of the medium (density of the medium, etc.)
and stays the same regardless of the medium. Thus, the wavelength of this wave in a given medium would be proportional to the speed in that medium.
For example, the speed of sound in materials with a larger density (e.g., water) is generally larger than that in materials with lower density (e.g., air.)
When a sound wave travels from air into water, the frequency of this wave would stay the same. However, since the speed of the wave would increase, the wavelength of this wave would also increase.
The main difference between beneficial and harmful friction is that beneficial friction is necessary for performing different activities while on the other hand, harmful effect of friction is destroy different parts of products and machines. examples of beneficial friction are walking, holding things, rubbing hands to produce heat, running etc whereas examples of harmful friction are destruction of sole, slipping, tearing of machine's part, Wet roads and Mudslides etc.
The equation a=F/m or the acceleration is equal to the net force of an object divided by that object's mass, is an equation derived and explained by Sir Issac Newton's second law of motion. Newton's second law of motion states that the force of an object is equal to the mass times the acceleration of that object.
Option B (remain vertically under the plane) is the correct option.
Explanation:
A flare would follow a particle trajectory with horizontal direction somewhat like airplane velocity as well as initial maximum motion as null but instead, gravity will induce acceleration. It would be lowered vertically underneath the plane before flare had already sunk to something like the surface.
There is no different movement in the airplane nor even the flash. And none of them can change its horizontal level.
Some other alternatives are given really aren't linked to the specified scenario. So choice B is the perfect solution to that.