A typical 100 W incandescent light bulb emits about 3 Watts of light. How much force is exerted on a page of 8.5″x11″ white printer paper 0.

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A typical 100 W incandescent light bulb emits about 3 Watts of light. How much force is exerted on a page of 8.5″x11″ white printer paper 0.8 m away? Assume the paper reflects 80% f the light that hits it. g

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Thu Thủy 4 years 2021-08-05T20:47:07+00:00 1 Answers 12 views 0

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  1. Adela
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    2021-08-05T20:48:55+00:00
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    Answer: 0.0169J/s-m of force will be exerted per sec per meter displacement of the paper

    Explanation:

    Power p = 3W

    Distance r = 0.8m

    Intensity = p/4¶r^2

    Intensity = 3/(4×3.142×0.8^2) = 0.373W/m2

    The paper is 8.5″ by 11″

    Converting to metre becomes

    0.2032m by 0.2794m

    Are of paper = 0.2032×0.2794 = 0.0568m2

    80% of the light reflected is,

    0.8×0.373 = 0.2984W/m2

    Energy per sec In the reflected light is 0.2984×0.0568 = 0.0169J/s

    Force = energy per sec per unit displacement of paper

    = 0.0169J/s-m

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