C.
The kilogram SI unit is based off an original prototype that is kept in France. The prototype itself is based off the mass of water under special conditions for temperature as well as pressure.
(b) 71%
The thermal efficiency of a Carnot heat engine is given by:

where
W is the useful work done by the engine
is the heat in input to the machine
In this problem, we have:
is the heat absorbed
is the work done (175 kJ is the heat released to the sink, therefore the work done is equal to the difference between the heat in input and the heat released)
So, the efficiency is

(a) 
The efficiency of an engine can also be rewritten as

where
is the absolute temperature of the cold sink
is the temperature of the source
In this problem, the temperature of the sink is

So we can re-arrange the equation to find the temperature of the source:

Answer:
Explanation:
Given
Velocity = 388m/s
Height S = 2.89m
Required
Time
Using the equation of motion
S =ut+1/2gt²
2.89 = 388t+1/2(9.8)t²
2.89 = 388t+4.9t²
Rearrange
4.9t²+388t-2.89 =0
Factorize
t = -388±√388²-4(4.9)(2.89)/2(4.9)
t= -388±√(388²-56.644)/9.8
t = -388±387.93/9.8
t =0.073/9.8
t = 0.00744 seconds
Answer:
Temperature of the sink will be 191.1 K
Explanation:
We have given that heat withdrawn form the source = 10 KJ
Work done = 3 KJ
We know that efficiency is given by

Higher temperature is given by 
We have to find the lower temperature 
We know that efficiency is also given by

So 
So temperature of the sink will be 191.1 K
Answer:
The sound travels differently in different medium according the density of the medium.
Explanation:
The sound travels faster in dense medium and can be heard by the vibration of the bone present in the ear. The ear plugs reduce the sound intensity in both medium water and on land (air).
In air the sound is not heard properly due to the earplugs that stops the as the vibration are not able to produce as sound is not able to reach to middle ear, but Navy researchers have discovered that sound under water is heard by the bone present behind the ear, vibrations mastoid.