The drinking water needs of an office are met by cooling tab water in a refrigerated water fountain from 23 to 6°C at an average rate of 10 kg/h. If the COP of this refrigerator is 3.1, the required power input to this refrigerator is (a) 197W
(b) 612W
(c) 64W
(d) 109W
(e) 403W
Answers
Answer:
The correct option is;
(c) 64W
Explanation:
Here we have the Coefficient Of Performance, COP given by
The heat change from 23° to 6°C for a mass of 10 kg/h which is equivalent to 10/(60×60) kg/s or 2.78 g/s we have
= m·c·ΔT = 2.78 × 4.18 × (23 - 6) = 197.39 J
Therefore, plugging in the value for in the COP equation we get;
which gives
Since we were working with mass flow rate then the power input is the same as the work done per second and the power input to the refrigerator = 63.674 J/s ≈ 64 W.
The power input to the refrigerator is approximately 64 W.
Answer:
Win = 64 W ... Option C
Explanation:
Given:-
- The water is cooled in the refrigerator with delta temperature, ΔT=(23 - 6 )
- The flow rate of the refrigerated water is flow ( m ) = 10 kg/h
- The COP of the refrigerator is = 3.1:
Find:-
the required power input to this refrigerator is
Solution:-
- The COP - The coefficient of performance of a refrigerator is a quantity that defines the efficiency of the system. The COP is given as:
COP = QL / Win
Where,
QL : The rate of heat loss
Win : The input power required
- The rate of heat loss can be determined from first law of thermodynamics.
Qin - Wout = flow (m)*c*ΔT
Where,
Qin = - QL ... Heat lost.
c : The heat capacity of water = 4,200 J / kg°C
- There is no work being done on the system so, Wout = 0
-QL = flow (m)*c*ΔT
-QL = ( 10 / 3600 )*4200*( 6 - 23 )
QL = 198.33 W
- The required power input ( Qin ) would be:
Win = QL / COP
Win = 198.33 / 3.1
= 63.97 W ≈ 64 W
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Explanation:
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Explanation:
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Answers
The initial velocity is 12.34 m/s
Explanation:
The vertical component of the initial velocity determines the maximum height.
The formula to apply is : v²=u²+2as , where
v=y-component, final velocity = 0 m/s
u= y-component of the initial velocity = ?
s= distance traveled = 2.3 m
a=acceleration due to gravity = -9.81 m/s²
Using the values in the equation
v²=u²+2as
0²=u²+2×2.3×-9.81
0=u²-45.126
45.126=u²
√45.126= u
6.7175 m/s
The vertical component of velocity is given by;
velocity*sin(angle with horizontal)
velocity=6.7175 / sin 33°
=12.338 m/s
=12.34 m/s
Learn More
Finding Initial velocity :brainly.com/question/1858995
Keywords : angle, maximum height, initial velocity, friction
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Answers
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Explanation:
Answers