Answer: Plz mark me brainliest i am 12 and i've never been marked brainliest.
Explanation:
Sound will echo in an empty room because if there is nothing to stop the sound from reflecting between hard surfaces, such as the walls, windows, ceiling, and floor . Since each surface is not a perfect reflector, some of the sound energy will be absorbed by the surface.
Answer:
<h2>92.86 kg </h2>
Explanation:
lThe mass of an object given only it's force and acceleration can be found by using the formula

f is the force
a is the acceleration
From the question
f = 195 N
a = 2.1 m/s
We have

We have the final answer as
<h3>92.86 kg</h3>
Hope this helps you
Answer:
Option A applies.
A. Greater than its escape speed from the mass within the volume
Explanation:
Here it is mentioned that the spherical volume is large enough for the space to be considered as homogeneous. Also, the pressure within the volume is negligible, so that will not result into the re collapse of the Universe. Now as per our knowing, Hubble's Law relates the average speed of the particle to the distance R between the Earth and the particle. So, if the particle's speed is greater than it's escape speed from the mass within the volume, then the Universe is bound to re collapse back again. Option A applies.
The work done by the battery is equal to the charge transferred during the process times the potential difference between the two terminals of the battery:

where q is the charge and

is the potential difference.
In our problem, the work done is W=39 J while the potential difference of the battery is

, so we can find the charge transferred by the battery:
Answer:
a)η = 69.18 %
b)W= 1210 J
c)P=3967.21 W
Explanation:
Given that
Q₁ = 1749 J
Q₂ = 539 J
From first law of thermodynamics
Q₁ = Q₂ +W
W=Work out put
Q₂=Heat rejected to the cold reservoir
Q₁ =heat absorb by hot reservoir
W= Q₁- Q₂
W= 1210 J
The efficiency given as



η = 69.18 %
We know that rate of work done is known as power


P=3967.21 W