An elevator held by a single cable is ascending but slowing down. Is the work done by tension positive, negative, or zero? What
1 answer:
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Answer:
B. QC > 0; QH < 0
Explanation:
Given that there are two reservoir of energy.
Sign convention for heat and work :
1.If the heat is adding to the system then it is taken as positive and if heat is going out from the system then it is taken as negative.
2. If the work is done on the system then it is taken as negative and if the work is done by the system then it is taken as positive.
From hot reservoir heat is going out that is why it is taken as negative
From cold reservoir heat is coming inside the reservoir that is why it is taken as positive
That is why the answer will be
,
Answer:
No. of laps of Hannah are 7 (approx).
Solution:
According to the question:
The total distance to be covered, D = 5000 m
The distance for each lap, x = 400 m
Time taken by Kara,
Time taken by Hannah,
Now, the speed of Kara and Hannah can be calculated respectively as:
Time taken in each lap is given by:
t = 500 s
So, Distance covered by Hannah in 't' sec is given by:
No. of laps taken by Hannah when she passes Kara:
≈ 7 laps