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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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Is gravity a force ?
alexandr402 [8]

Answer:

Gravity ( gravity , weight, traction force) is the force acting on any body on or near the surface of the celestial body directed at its center. Gravity, that is, the force with which the earth , moon , planets, and other celestial bodies or their systems act on other bodies, is theoretically exercised at any distance, but is practically examined on the surface of these bodies as well as at short distances.

6 0
3 years ago
A rectangular certificate has a perimeter of 32 inches. Its area is 63 square inches. What are the dimensions of the certificate
irina1246 [14]
Perimeter = 2 ( L + W )
32 = 2 ( L + W )
16 = L + W
L = 16 - W

Area = L W
63 = L W
63 = (16-W) W
63 = 16W - W²
-W² + 16 W - 63 = 0
By factorizing W = 9 or W = 7
So the dimensions are 7 and 9
3 0
2 years ago
An objects mechanical energy never changes it simply changes between
tatiyna
Actually moving and not. It is the sum of potential and kinetic energy.
4 0
3 years ago
. a boat can travel in still water. (a) if the boat points directly across a stream whose current is what is the velocity (magni
mixer [17]

a) The velocity of the boat relative to the shore is 3.40 m/s and b) The position of the boat relative to its point of origin after 3s is 10.20m.

Here it is given that the speed of the boat (x) = 2.20m/s

The speed of the stream current (y) = 1.20m/s

a) We have to find the velocity of the boat relative to the shore.

The speed of the boat = x + y

                                    = 2.20 + 1.20

                                    = 3.40m/s

b) Now we have to find the position of the boat after 3s

The formula for speed:

Speed = Distance/ Time

distance = speed × time

speed = 3.40m/s

Time = 3s

distance = 3.40 × 3

              = 10.20 m

Therefore we get a) speed as 3.40m/s and b) distance as 10.20m.

To know more about the boat and stream refer to the link given below:

brainly.com/question/382952

#SPJ4

 

8 0
1 year ago
The loop is in a magnetic field 0.20 T whose direction is perpendicular to the plane of the loop. At t = 0, the loop has area A
love history [14]

Answer:

Part a)

EMF = 14 \times 10^{-3} V

Part b)

EMF = 15.67 \times 10^{-3} V

Explanation:

As we know that magnetic flux through the loop is given as

\phi = B.A

now we have

\phi = B\pi r^2

now rate of change in flux is given as

\frac{d\phi}{dt} = B(2\pi r)\frac{dr}{dt}

now we know that

A = \pi r^2

0.285 = \pi r^2

r = 0.30 m

Now plug in all data

EMF = (0.20)\times 2\pi\times (0.30) \times (0.037)

EMF = 14 \times 10^{-3} V

Part b)

Now the radius of the loop after t = 1 s

r_1 = r_0 + \frac{dr}{dt}

r_1 = 0.30 + 0.037

r_1 = 0.337 m

Now plug in data in above equation

EMF = (0.20)\times 2\pi\times (0.337) \times (0.037)

EMF = 15.67 \times 10^{-3} V

5 0
3 years ago
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