Answer:
maybe a. what you think . about that
Answer:
![\Delta S=1.69J/K](https://tex.z-dn.net/?f=%5CDelta%20S%3D1.69J%2FK)
Explanation:
We know,
..............(1)
where,
η = Efficiency of the engine
T₁ = Initial Temperature
T₂ = Final Temperature
Q₁ = Heat available initially
Q₂ = Heat after reaching the temperature T₂
Given:
η =0.280
T₁ = 3.50×10² °C = 350°C = 350+273 = 623K
Q₁ = 3.78 × 10³ J
Substituting the values in the equation (1) we get
![0.28=1-\frac{Q_2}{3.78\times 10^{3}}](https://tex.z-dn.net/?f=0.28%3D1-%5Cfrac%7BQ_2%7D%7B3.78%5Ctimes%2010%5E%7B3%7D%7D)
or
![\frac{Q_2}{3.78\times 10^3}=0.72](https://tex.z-dn.net/?f=%5Cfrac%7BQ_2%7D%7B3.78%5Ctimes%2010%5E3%7D%3D0.72)
or
![Q_2=3.78\times 10^3\times0.72](https://tex.z-dn.net/?f=Q_2%3D3.78%5Ctimes%2010%5E3%5Ctimes0.72)
⇒ ![Q_2 =2.721\times 10^3 J](https://tex.z-dn.net/?f=Q_2%20%3D2.721%5Ctimes%2010%5E3%20J)
Now,
The entropy change (
) is given as:
![\Delta S=\frac{\Delta Q}{T_1}](https://tex.z-dn.net/?f=%5CDelta%20S%3D%5Cfrac%7B%5CDelta%20Q%7D%7BT_1%7D)
or
![\Delta S=\frac{Q_1-Q_2}{T_1}](https://tex.z-dn.net/?f=%5CDelta%20S%3D%5Cfrac%7BQ_1-Q_2%7D%7BT_1%7D)
substituting the values in the above equation we get
![\Delta S=\frac{3.78\times 10^{3}-2.721\times 10^3 J}{623K}](https://tex.z-dn.net/?f=%5CDelta%20S%3D%5Cfrac%7B3.78%5Ctimes%2010%5E%7B3%7D-2.721%5Ctimes%2010%5E3%20J%7D%7B623K%7D)
![\Delta S=1.69J/K](https://tex.z-dn.net/?f=%5CDelta%20S%3D1.69J%2FK)
As per Newton's law of cooling we know that
![\frac{\Delta T}{dt} = k(T_avg - T_s)](https://tex.z-dn.net/?f=%5Cfrac%7B%5CDelta%20T%7D%7Bdt%7D%20%3D%20k%28T_avg%20-%20T_s%29)
in 5 hours the body temperature becomes 79.6 from 84.4
while the surrounding temperature is given as 68 degree F
now from above formula
![\frac{84.4 - 79.6}{5} = k (\frac{84.4 + 79.6}{2} - 68)](https://tex.z-dn.net/?f=%5Cfrac%7B84.4%20-%2079.6%7D%7B5%7D%20%3D%20k%20%28%5Cfrac%7B84.4%20%2B%2079.6%7D%7B2%7D%20-%2068%29)
![0.96 = k(14)](https://tex.z-dn.net/?f=0.96%20%3D%20k%2814%29)
now let say the person died "t" time ago
now we will have
![\frac{98.6 - 84.4}{t} = k (\frac{98.6 + 84.4}{2} - 68)](https://tex.z-dn.net/?f=%5Cfrac%7B98.6%20-%2084.4%7D%7Bt%7D%20%3D%20k%20%28%5Cfrac%7B98.6%20%2B%2084.4%7D%7B2%7D%20-%2068%29)
![\frac{14.2}{t} = k(23.5)](https://tex.z-dn.net/?f=%5Cfrac%7B14.2%7D%7Bt%7D%20%3D%20k%2823.5%29)
![\frac{14.2}{t} = \frac{0.96}{14}(23.5)](https://tex.z-dn.net/?f=%5Cfrac%7B14.2%7D%7Bt%7D%20%3D%20%5Cfrac%7B0.96%7D%7B14%7D%2823.5%29)
![t = 8.8 hours = 9hours (approx)](https://tex.z-dn.net/?f=t%20%3D%208.8%20hours%20%3D%209hours%20%28approx%29)
so he died at approx 5 Am in morning
KE = 1/2mv^2
m = 2000
v = 30m/s
1/2*2000*30^2=
1000*900 = 900,000kgm^2/s^2
The mass of the rider 1 is 4 g.
<h3>
The use of a rider in mass measurement</h3>
Rider is a metallic wire piece which is of certain mass and can be bent . It can move the beam of the Paul Bunge Balance.
The riders are the sliding pointers positioned on top of the beams to show the pan and beam weight in grams.
<h3>Mass of the rider 1</h3>
The mass of the rider 1 is obtained by subtracting mass of riders as show below.
mass of rider 1 = mass of object - (mass of rider 2 + mass of rider 3)
mass of rider 1 = 694 g - (600 g + 90 g)
mass of rider 1 = 694 g - 690 g
mass of rider 1 = 4 g
Thus, the mass of the rider 1 is 4 g.
Learn more about use of riders in mass measurement here: brainly.com/question/1747339
#SPJ1