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mestny [16]
3 years ago
12

What is the maximum efficiency of a heat engine whose operating temperatures are 590 ?c and 325 ?c?

Physics
1 answer:
mina [271]3 years ago
7 0
 <span>The maximum possible efficiency, i.e the efficiency of a Carnot engine , is give by the ratio of the absolute temperatures of hot and cold reservoir. 
η_max = 1 - (T_c/T_h) 

For this engine: 
η_max = 1 - [ (20 +273)K/(600 + 273)K ] = 0.66 = 66% 

The actual efficiency of the engine is 30%, i.e. 
η = 0.3 ∙ 0.664 = 0.20 = 20 % 

On the other hand thermal efficiency is defined as the ratio of work done to the amount of heat absorbed from hot reservoir: 
η = W/Q_h 

So the heat required from hot reservoir is: 
Q_h = W/η = 1000J / 0.20 = 5000J</span>
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A truck covered 2/7 of a journey at an average speed of 40
sertanlavr [38]

Answer:

The amount of time for the whole journey is 8 hours.

Explanation:

A truck covered 2/7 of a journey at an average speed of 40  mph. Representing 1 the total of the trip traveled, then the rest of the distance traveled is calculated as: 1-\frac{2}{7} =\frac{5}{7}

So if the truck covered the remaining 200 miles at \frac{2}{7}, this means that \frac{5}{7} of the trip represents the 200 miles. So, to calculate the total distance traveled by the truck, you apply the following rule of three: if \frac{5}{7} of the route represents 200 miles, the integer 1 (which represents the total of the route), how many miles are they?

miles=\frac{1*200miles}{\frac{5}{7} } =\frac{7}{5} *200 miles

miles= 280

So the total distance traveled is 280 miles. Since speed is the relationship between the space traveled by an object and the time used for it (speed=\frac{distance}{time}), then if the average of the entire trip was 35 mph and the distance traveled 280 miles, the time is calculated as:

time=\frac{distance}{speed}=\frac{280 miles}{35 mph}

time= 8 h

<u><em> The amount of time for the whole journey is 8 hours.</em></u>

<u><em /></u>

6 0
3 years ago
Velocity is speed in a certain direction.<br><br> True<br> False
lara [203]
True if you look up the question Is velocity speed in a certain direction you would’ve gotten the answer but I’m pretty sure it’s true
6 0
3 years ago
Read 2 more answers
A charge of -5.02 nC is uniformly distributed on a thin square sheet of nonconducting material of edge length 21.8 cm. "What is
Maru [420]

Answer:

A charge of -5.02 nC is uniformly distributed on a thin square sheet of nonconducting material of edge length 21.8 cm. "What is the surface charge density of the sheet"?

Explanation:

Surface charge density is a measure of how much electric charge is accumulated over a surface. It can be calculated as the charge per unit area.

We will convert all parameters in SI units.

Charge = Q = -5.02nC

Q  = -5.02×10^{-9}C

As it is clear from question that Sheet is a square (All sides will be of equal length)

Area = A = (21.8×10^{-2}m) (21.8×10^{-2}m)  = 4.75×10^{-4}m²

A  = 4.75×10^{-4}m²

Surface charge density = Q/A

Surface charge density = (-5.02×10^{-9}C)/(4.75×10^{-4}m²)

Surface charge density = -1.057×10^{-5} Cm^{-2}

3 0
3 years ago
a horse moves a sleigh 1.00 kilometers by applying a horizontal 2000 Newton force on its harness for 45 minutes. what is the pow
tatyana61 [14]
--  If 2,000 newtons of force were applied through a distance of 1,000 meters,
then 2,000,000 newton-meters = 2,000,000 joules of work were done.

-- 45 minutes = (45 x 60) = 2,700 seconds

-- Power = (work) / (time) = (2,000,000 j) / (2,700 s) = <u>740.74 watts</u>

Interestingly, that's almost exactly 1 horsepower.  (0.99295... of 746 watts)
8 0
2 years ago
Diesel fuel is used in the engine of trucks that carry dirt fruit and other cargo. Fuel is burned in engines to make the motor m
Marina86 [1]

Answer: Fuel is burned in engines to make the motor move.

( Chemical to Mechanical )

Explanation:

during combustion of the diesel ( when the fuel is burnt in the engine of the vehicle, the diesel ( chemical energy ) is transformed or converted to Mechanical energy. This mechanical energy is what the truck uses in moving. Without the combustion of the fuel the vehicle won’t move and the combustion of diesel is achieved through compression unlike that of fuel.

4 0
3 years ago
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