Answer:
3.75 × 10⁻⁸ N
Explanation:
Given:
Intensity of the electromagnetic wave, I = 150 W/m²
Sides of the board = 25 cm (= 0.25 m) and 30 cm (= 0.30 m)
therefore,
the area of the rectangular box, A = 0.25 × 0.30 = 0.075 m²
Now,
force exerted on the card by the radiation, F =
here,
C is the speed of the light = 3 × 10⁸ m/s
on substituting the respective values, we get
F =
or
F = 3.75 × 10⁻⁸ N
The universal law of gravitation states that:
Every object in the universe attracts every other object with a force which is proportional to the product of their masses and inversely proportional to the square of distance between them.
It means that if the gravitational force is F, then if the distance is decreased by 5 times, then the new gravitation force is:
F/5² = F/25
The power expended is 500 W
Explanation:
First of all, we start by calculating the work done by the man in order to ascend: this is equal to the gravitational potential energy gained by the man, which is
where
m = 50 kg is the mass of the man
is the acceleration of gravity
is the change in height
Substituting,
Now we can calculate the power expended, which is given by
where
W = 2500 J is the work done
t = 5 s is the time elapsed
Substituting, we find
Learn more about power:
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