Answer:
0.237 (23.7 %)
Explanation:
The thermal efficiency of an engine is given by:
where
W is the useful work output of the engine
is the heat in input
Here we have:
and the work done is the total heat in input minus the heat exhausted:
So, the efficiency is
(23.7 %)
Answer: person C.
Explanation:
1) The frequency of the sound wave is perceived or detected as the pitch of the sound.
And the higher the frequency the the higher the pitch.
2) When a sound source is in motion there is an apparent change in the pitch perceived. This is the Doppler effect, which is defined as the change in the perception of the pitch in virtue of the relative motion between the listener and the emitter of the sound.
If the source of the sound is moving toward the listener, the pitch will be higher that if the sound is at rest. If the source of the sound is moving away from the listener, the pitch will be lower.
That is because the the motion of the emitter increases (or decreases, depending on whether the emitter is moving toward or away the listener) the speed of the sound waves and they arrive more frequently (or less frequently).
Then, since the sound is emitted by the motorbike and it is moving toward the person C, he will hear the highest pitch.
Answer:
1/ As a metal has higher melting point than a nonmetal has, we can guess that sample A is a metal.
2/ The melting point is over 1000 gradius Celcius: 1083 - it's not a low value. And as the sample conducts heat, it is not the element of period N3 in the periodic table, because elements in period 3 do not conduct electricity.
Explanation:
I can not see what the questions 2-3 in your picture is. I answered the question above the table: What can the student conclude about thenidentity of Sample A.
Answer:
Heat transfer during the process = 0
Work done during the process = - 371.87 KJ
Explanation:
Initial pressure 
= 0.02 bar
Initial temperature 
= 200 K
Final pressure 
= 0.14 bar
Gas constant for helium R = 2.077 
This is an isentropic polytropic process so temperature - pressure relationship is given by the following formula,
= ![[\frac{P_{2} }{P_{1} } ]^{\frac{\gamma - 1}{\gamma} }](https://tex.z-dn.net/?f=%5B%5Cfrac%7BP_%7B2%7D%20%7D%7BP_%7B1%7D%20%7D%20%5D%5E%7B%5Cfrac%7B%5Cgamma%20-%201%7D%7B%5Cgamma%7D%20%7D)
Put all the values in above formula we get,
⇒ 
= ![[\frac{0.14 }{0.02 } ]^{\frac{1.4 - 1}{1.4} }](https://tex.z-dn.net/?f=%5B%5Cfrac%7B0.14%20%7D%7B0.02%20%7D%20%5D%5E%7B%5Cfrac%7B1.4%20-%201%7D%7B1.4%7D%20%7D)
⇒ = 1.74
⇒ 
= 348.72 K
This is the final temperature of helium.
For isentropic polytropic process heat transfer to the system is zero.
⇒ ΔQ = 0
Work done W = m × ( - ) × 
⇒ W = 1 × ( 200 - 348.72 ) × 
⇒ W = 371.87 KJ
This is the work done in this process. here negative sign shows that work is done on the gas in the compression of gas.
Answer:
5m/s
Explanation:
equation for momentum is mass times velocity
25 x 5 = 125
