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bearhunter [10]
2 years ago
14

A heat engine is designed to do work. This is possible only if certain relationships between the heats and temperatures at the i

nput and output hold true. Which of the following sets of statements must apply for the heat engine to do work?
A) Qh < Qc and Th < Tc
B) Qh > Qc and Th < Tc
C) Qh < Qc and Th > Tc
D) Qh > Qc and Th > Tc

Part B
Find the work W done by the "ideal" heat engine.
Express W in terms of Qh and Qc
W=___________

Part C
The thermal efficiency e of a heat engine is defined as follows: e = W/Qh
Express the efficiency in terms of Qh and Qc.
e=____________
Physics
1 answer:
Tcecarenko [31]2 years ago
4 0

Answer:

Part A: D

Part B: W = Qh - Qc

Part C: e = 1 - Qc/Qh

Explanation:

The heat engine is the engine that transforms heat (Q) in work (W), and by the second law of the thermodynamics, its efficiency can not be 100%, it means that some heat must be dissipated.

Part A:

The engine works with two sources of heat, one hot (Qh) at a hot temperature (Th) and another cold (Qc) at a cold temperature (Tc). It is necessary so, the hot source will give energy to the fluid of the engine, and the cold source will be the source where these heat will dissipate and the fluid will return to its original temperature. So,

Qh > Qc, and Th > Tc

Part B:

The ideal heat engine is the one that can use the most amount of heat to transform it at work. It is characterized by Qh/Qc = Th/Tc.

The work is the useful energy, so it is the total heat (Qh) less the heat dissipated (Qc):

W = Qh - Qc

Part C:

The effiency is the useful energy divided by the total energy. Because W = Qh - Qc:

e = W/Qh

e = (Qh - Qc)/Qh

e = Qh/Qh - Qc/Qh

e = 1 - Qc/Qh

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Sidana [21]

To develop this problem, it is necessary to apply the concepts related to the description of the movement through the kinematic trajectory equations, which include displacement, velocity and acceleration.

The trajectory equation from the motion kinematic equations is given by

y = \frac{1}{2} at^2+v_0t+y_0

Where,

a = acceleration

t = time

v_0 = Initial velocity

y_0 = initial position

In addition to this we know that speed, speed is the change of position in relation to time. So

v = \frac{x}{t}

x = Displacement

t = time

With the data we have we can find the time as well

v = \frac{x}{t}

t = \frac{x}{v}

t = \frac{18.6}{34}

t = 0.547s

With the equation of motion and considering that we have no initial position, that the initial velocity is also zero then and that the acceleration is gravity,

y = \frac{1}{2} at^2+v_0t+y_0

y = \frac{1}{2} gt^2+0+0

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y = \frac{1}{2} 9.8*0.547^2

y = 1.46m

Therefore the vertical distance that the ball drops as it moves from the pitcher to the catcher is 1.46m.

6 0
3 years ago
1. A pendulum has a period of 3 seconds. What's its frequency? 2. A pendulum has a frequency of 0.25 Hz. What's its period? 3. A
RideAnS [48]

Answer:

(1) 0.333 Hz

(2) 4 sec

(3) 2 sec, 0.5 Hz

Explanation:

(1) We have given time period of pendulum is 3 sec

So T = 3 sec

Frequency will be equal to f=\frac{1}{T}=\frac{1}{3}=0.333Hz

(2) Frequency of the pendulum is given f = 0.25 Hz

Time period is equal to T=\frac{1}{f}=\frac{1}{0.25}=4sec

(3) It is given that a pendulum makes 10 back and forth swings in 20 seconds

So time taken to complete 1 back and forth swings = =\frac{20}{10}=2sec

So time period T = 2 sec

Frequency will be equal to f=\frac{1}{T}=\frac{1}{2}=0.5Hz

6 0
3 years ago
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RideAnS [48]

Answer:

7 / 1

Explanation:

The ratio of their amplitude = one-seventh and the ratio of their amplitude = the ratio of their wavelength

Ax / Ay = λx / λy  = 1 / 7

λy / λx = 7 / 1

7 0
3 years ago
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HOPE IT HELPS...

5 0
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Leto [7]

Answer:

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Explanation:

Hope this helps :)

7 0
3 years ago
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