HW 3 Begin Date: 9/12/2018 5:00:00 PM -- Due Date: 9/24/2018 11:59:00 PM End Date: 12/31/2018 12:00:00 AM (10%) Problem 10: Samu
1 answer:
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Answer:
q = 13 C
Explanation:
Given that,
Electric current, I = 20 A
The starter motor runs for 0.65 s before the car engine starts up.
We need to find how much of electric charge passes through the starter motor. Let it is q.
Electric current = electric charge/time
So, 13 C of electric charge passes through the starter motor.
Answer:
For the Carnot air conditioner working as a heat pump between 63 and 100°F , It would transfer 3.125 Joules of heat for each Joule of electric energy supplied.
Explanation:
The process described corresponds to a Carnot Heat Pump. A heat pump is a devices that moves heat from a low temperature source to a relative high temperature destination. <em>To accomplish this it requires to supply external work</em>.
For any heat pump, the coefficient of performance is a relationship between the heat that is moving to the work that is required to spend doing it<em>.</em>
For a Carnot Heat pump, its coefficient of performance is defined as:
Where:
- T is the temperature of each heat deposit.
- The subscript H refers to the high temperature sink(in this case the outdoors at 100°F)
- The subscript L refers to the low temperature source (the room at 63°F)
Then, for this Carnot heat pump:
So for each 3.125 Joules of heat to moved is is required to supply 1 Joule of work.