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Photons and force

[Deleted User][Deleted User] Posts: 12,830
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in General Discussion #1
A man on the tv said that asteroids were subject to a minute force which was enough to move them caused by being impacted by photons from the sun. But if photons have no mass, how can they create force if force is mass times acceleration ?

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    JohnbeeJohnbee Posts: 4,019
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    #2
    Good question mate. It is for answering that mystery that bamboozled scientists for ages, that Einstein received the Nobel prize. What happens is the photoelectric effect, where because light has energy, when it hits a metal, electrons are emitted. Electrons shoot out and they of course do have mass, so Bob's yr uncle.

    A web search will give fuller info and some equations.
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    gkecgkec Posts: 788
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    #3
    Although photons have no rest mass they have energy which means they have relativistic mass (E=mc2) so have momentum which can be imparted on another object e.g. asteroid.
    This is known as radiation pressure.
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