Answer:
2f
Explanation:
The formula for the object - image relationship of thin lens is given as;
1/s + 1/s' = 1/f
Where;
s is object distance from lens
s' is the image distance from the lens
f is the focal length of the lens
Total distance of the object and image from the lens is given as;
d = s + s'
We earlier said that; 1/s + 1/s' = 1/f
Making s' the subject, we have;
s' = sf/(s - f)
Since d = s + s'
Thus;
d = s + (sf/(s - f))
Expanding this, we have;
d = s²/(s - f)
The derivative of this with respect to d gives;
d(d(s))/ds = (2s/(s - f)) - s²/(s - f)²
Equating to zero, we have;
(2s/(s - f)) - s²/(s - f)² = 0
(2s/(s - f)) = s²/(s - f)²
Thus;
2s = s²/(s - f)
s² = 2s(s - f)
s² = 2s² - 2sf
2s² - s² = 2sf
s² = 2sf
s = 2f
Answer:
The work done on the box is 100 Nm
The power is 20 Nm/s
Explanation:
There is a force 25 newtons moves a box a distance of 4 meters in
5 seconds
The work done on the box is the product of the force and the distance
that the box moves ⇒ <em>work = force × distance</em>
The force = 25 newtons
the distance = 4 meters
Work = 25 × 4 = 100 NM
<em>The work done on the box is 100 Nm</em>
<em></em>
The force moves the box 4 meters in 5 seconds
The power is the rate of work
<em>The power = work ÷ time</em>
The work = 100 Nm
The time = 5 seconds
The power = 100 ÷ 5 = 20 Nm/s
<em>The power is 20 Nm/s</em>
Its resistor :}...............
The answer is : 35 to 52 minutes.
Hope this helps!
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