They can't hear an echo in small room because in it the sound can't be reflected back. For an echo of a sound to be heard,the minimum distance between the source of sound and the walls of the roomshould be 17.2 m. Obviously,in asmall room echoes cannot beheard.
Answer:
W=1055N
Explanation:
In order to solve this problem, we must first do a drawing of the situation so we can visualize theh problem better. (See attached picture)
In this problem, we will ignore the board's weight. As we can see in the free body diagram of the board, there are only three forces acting on the system and we can say the system is in vertical equilibrium, so from this we can say that:

so we can do the sum now:

when solving for the Weight W, we get:

and now we can substitute the given data, so we get:
W=410N+645N
W=1055N
Elastic collision is when kinetic energy before = kinetic energy after
Ek= 1/2mv^2
total before
Ek=1/2(2)(2.2^2) = 4.84 J
total after
Ek= 1/2(2+4)(v^2) = 3v^2
Before = after
4.84=3v^2 | divide by 3
121/75 = v^2 | square root both sides
v=1.27 m/s
Answer:

<h3>B. Speed at which it leaves the ground</h3>
Answer:
4. Sterilization
Explanation:
A reservoir refers to the breeding ground or natural habitat of micro living organisms such as bacterias, fungi, worms, etc. Thus, a reservoir hosts or harbours pathogens and usually serves as a source of infection to other living organisms.
On the other hand, a source of infection refers to a contaminated material from which a disease can be acquired by another living organism.
Pathogen refers to a disease causing organism or substance such as fungi, protozoa, bacteria, virus, etc.
Sterilization simply means to be free from all organisms either pathogenic or nonpathogenic organisms such as spores and viruses.
An autoclave can be defined as a chamber (container) designed to expose an equipment to steam i.e a moisture at high heat and pressure for a specific period of time.
Basically, an autoclave is a container or chamber that is strongly heated and as a result, it is typically used for the sterilization of various laboratory and medical equipments using steam under pressure and high temperature.
This ultimately implies that, an autoclave avails laboratory scientist and other end users the ability to disinfect or sterilize equipments by exposing them to moisture at high heat and pressure for a specific period of time.