I need number two only
2 answers:
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Answer:
7revolutions
Explanation:
Given parameters:
Initial revolution = 250rpm
Final revolution = 150rpm
Time = 4.2s
Unknown:
Number of revolutions that occur at this time = ?
Solution:
To solve this problem;
let us find the change in revolution = 250rpm - 150rpm = 100rpm
Convert the time to seconds;
60s makes 1 minute
4.2s will make = 0.07min
So;
The number of revolutions at this time = 100rpm x 0.07min
= 7revolutions
Answer: 5.34 MJ
Explanation: The window is a rectangle with area:
A = 1.1(1.5)
A = 1.65 m²
We know that only 0.9 kW/m² reaches Earth so:
P =
P = 1.485 x 10³ W
Watts is an unit of Power and it can also be written as J/s.
An hour has 3600s or 3.6 x 10³s, so:
E = 1.485 x 10³ (3.6 x 10³s)
E = 5.346 x 10⁶ J
Mega is equal to 10⁶, then:
E = 5.35 MJ
A 1.1 m by 1.5 m window collects, during 1 hour of daylight, 5.35 MJ