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cupoosta [38]
3 years ago
9

A heat engine does 30 j of work per cycle while exhausting 50 j of waste heat. what is the engine's thermal efficiency?

Physics
1 answer:
vazorg [7]3 years ago
4 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 raindrop falls to the ground from a rain cloud at an altitude of 3000 meters.
shutvik [7]

Assuming the raindrop was stationary relative to the vertical distance to the ground at the start:

D=0.5at where d is distance, a is acceleration and t is time

D is 300 meters

a is 9.8 meter/sec squared

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t = 61.2 seconds

v=at where v is velocity

a is 9.8 meters per second squared

t is 61.2 seconds

solve for v

v = 600 meters per second.

If it had an initial vertical velocity (v0) at the start :

d= 0.5at+v0t

and

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8 0
3 years ago
How does a substance's temperatura chanté when the average kinetic energy of its particles increases? When it decreases?
Aleks [24]
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The opposite is also true. The less something moves, it will have less Kinetic energy and the colder it will get. 

If you're having trouble understanding this, think of it like how the particles in water move compared to how the particles in ice move. The particles in water are free flowing and can move wherever they want. If they get colder, they won't move as much, and eventually they'll stop flowing around, forming a solid and staying colder than the water will get.
7 0
3 years ago
Which statement is true according to Hooke's law?
Mkey [24]

Hooke's law:

F = -kx

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Looking at Hooke's law, the magnitude of the force is directly proportional to its displacement; that is to say, if the displacement increases, so does the magnitude of the spring force, and if the magnitude of the force increases, this necessitates an increase in the displacement.

1. As the force on a spring increases, the distance it stretches decreases.

An increase in force necessitates an increase in displacement. This statement is false.

2. As the force on a spring increases, the distance it stretches increases.

An increase in force necessitates an increase in displacement. This statement is true.

3. As the force on a spring increases, the spring's length remains unchanged.

An increase in force necessitates an increase in displacement. This statement is false.

4. The distance a spring stretches has nothing to do with how much force is applied to it.

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3 0
3 years ago
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Wittaler [7]

Answer:

option (D)

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the distance between you and your image = 2 x 2.4 = 4.8 m

5 0
3 years ago
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andrew-mc [135]
A. 
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