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Snezhnost [94]
3 years ago
12

A heat engine has a cold reservoir of 250°C and a hot reservoir of 715°C. What is the efficiency of the engine?

Physics
2 answers:
Margarita [4]3 years ago
6 0
If the heat engine is a perfect carnot cycle engine, then
efficiency = (T2-T1)/T2  
where T1=temperature of cold reservoir ( ° K) = 250+273.15 = 523.15
           T2=temperature of hot reservoir ( ° K)  = 715+273.15 = 988.15

Therefore
efficiency = (T2-T1)/T2 = (988.15-523.15)/988.15 = 0.4706 = 47% 

Note: this is the theoretical maximum efficiency of a perfect heat engine.  Real-life engines do not achieve this value.
Illusion [34]3 years ago
5 0

The answer is A. 65.0% for plato users, i got 100% on the test  :)

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Answer:

laser pointer does not make use of total internal reflection

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2 years ago
Why society might initially reject a new scientific theory?
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I was about to say:  because people generally get comfortable with
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But then I thought about it a little bit more, and I have a different answer.

"Society" might initially reject a new scientific theory, because 'society'
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There may be very good reasons that some particular a new scientific theory
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6 0
3 years ago
Say you want to make a sling by swinging a mass M of 2.3 kg in a horizontal circle of radius 0.034 m, using a string of length 0
ycow [4]

Answer:

T = 764.41 N

Explanation:

In this case the tension of the string is determined by the centripetal force. The formula to calculate the centripetal force is given by:

F_c=m\frac{v^2}{r}  (1)

m: mass object = 2.3 kg

r: radius of the circular orbit = 0.034 m

v: tangential speed of the object

However, it is necessary to calculate the velocity v first. To find v you use the formula for the kinetic energy:

K=\frac{1}{2}mv^2

You have the value of the kinetic energy (13.0 J), then, you replace the values of K and m, and solve for v^2:

v^2=\frac{2K}{m}=\frac{2(13.0J)}{2.3kg}=11.3\frac{m^2}{s^2}

you replace this value of v in the equation (1). Also, you replace the values of r and m:

F_c=(2.3kg)(\frac{11.3m^2/s^2}{0.034})=764.41N

hence, the tension in the string must be T =  Fc = 764.41 N

5 0
3 years ago
a man crossed a road 8.25m wide at a speed of 2.01m/s,how long does it take to get man to cross the road​
Svetradugi [14.3K]

Answer:

t = 4.1 seconds

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Width of road which is to be crossed by a man is 8.25 m, it means it is distance to be covered.

Speed of man is 2.01 m/s

We need to find the time taken by the man to cross the road. It is a concept of speed. Speed of a person is given by total distance covered divided by time taken. So,

v=\dfrac{d}{t}

t is time taken

t=\dfrac{d}{v}\\\\t=\dfrac{8.25}{2.01}\\\\t=4.1\ s

So, the time taken by the man to cross the road is 4.1 seconds.

5 0
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Harrizon [31]

Answer:

He is warmed up now

Explanation:

His muscles are better and stretched now

3 0
3 years ago
Read 2 more answers
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