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irinina [24]
3 years ago
5

Light of intensity 2.00 W/m2 passes through the pupil of one of your eyes and eventually falls on your retina. The radius of the

pupil is controlled by the iris. In a human eye, the radius of the pupil can vary from about 1.0 mm to about 3.5 mm. The area of the opening can be calculated from pi (3.1416) times the radius squared. If your pupil is open to a radius of 2.5 mm, how much light energy passes through in one minute
Physics
1 answer:
lord [1]3 years ago
3 0

Answer:

Explanation:

Intensity of light, I = 2 W/m²

radius of pupil open, r = 2.5 mm = 2.5 x 10^-3 m

time, t = 1 min = 60 second

Energy passes, E = intensity x area x time

E = 2 x 3.14 x 2.5 x 2.5 x 10^-6 x 60

E = 2.36 x 10^-3 Joule

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Speed=distance/time, rearranging gives speed*time=distance therefore the first section of the journey yielded a total distance of 40km, the second journey was stated to be 20km which was completed in (20/30)*60=40minutes. Therefore the total journey was 60km which was completed in 1hr40 minutes so the average speed was (60/1.66..)=36km/h.
8 0
3 years ago
Point X is midway between the charges. In what section of the line will there be a point where the resultant electric field is z
Fiesta28 [93]

Answer:

I believe the answer is in fact section (VW) on the line where the electric field result will be zero.

Explanation:

The direction of the electric field due to a positive charge is away from it and the direction of the electric field due to a negative one is towards it.

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3 years ago
A tortoise can run with a speed of 0.14 m/s, and a hare can run 20 times as fast. In a race, they both start at the same time, b
Reptile [31]

speed of tortoise is given as v1 = 0.14 m/s

speed of hare is given as v2 = 20*0.14 = 2.8 m/s

now let say the total length of the path is "d"

so the total time taken by the tortoise to cover this

t = \frac{d}{0.14}

now given that hare took rest for 1 min

so total time of run for hare is (t - 60)s

so the distance that hare covered is given by

d - 0.30 = 2.8 * (t - 60)

now by above two equations

d - 0.30 = 2.8 * \frac{d}{0.14} - 168

168 - 0.30 = (20 - 1)d

d = 8.82 m

and the time t is given by

t = \frac{8.82}{0.14}

t = 63 s

so part a)

t = 63 s

part b)

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4 0
3 years ago
A proton, moving north, enters a magnetic field. Because of this field, the proton curves downward. We may conclude that the mag
PIT_PIT [208]

Answer:

towards the west

4 0
3 years ago
A force of 6600 N is exerted on a piston that has an area of 0.010 m2
sveticcg [70]

Answer:

Choice A: approximately 0.015\; \rm m^2, assuming that the two pistons are connected via some confined liquid to form a simple machine.

Explanation:

Assume that the two pistons are connected via some liquid that is confined. Pressure from the first piston:

\displaystyle P_1 = \frac{F_1}{A_1} = \frac{6.600\times 10^3\; \rm N}{1.0\times 10^{-2}\; \rm m^{2}} = 6.6\times 10^{5}\; \rm N \cdot m^{-2}.

By Pascal's Principle, because the first piston exerted a pressure of 6.6\times 10^{5}\; \rm N \cdot m^{-2} on the liquid, the liquid will now exert the same amount of pressure on the walls of the container.

Assume that the second piston is part of that wall. The pressure on the second piston will also be 6.6\times 10^{5}\; \rm N \cdot m^{-2}. In other words:

P_2 = P_1 = 6.6\times 10^{5}\; \rm N \cdot m^{-2}.

To achieve a force of 9.900 \times 10^3\; \rm N, the surface area of the second piston should be:

\displaystyle A_2 = \frac{F_2}{P_2} = \frac{9.900\times 10^{3}\; \rm N}{6.6\times 10^5\; \rm N \cdot m^{-2}} \approx 0.015\; \rm m^{2}.

4 0
3 years ago
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