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Article #1497Re: questions about light
From: Rick Matthews
Date: Mon, 02 May 1994 17:48
Date: Mon, 02 May 1994 17:48
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1638 bytes
Edward Van Nostrand (evannost@CALVIN.STEMNET.NF.CA) wrote: : Just a comment about your answer to 2. below : > >2. If light is a particle, when it leaves a flashlight why doesn't it : > >have enough momentum to push the flashlight backward? : > : > No mass, no momentum, no recoil. : > : Though light doesn't have mass it still has momentum. This is the I picked this discussion up in the middle, but... Light does have mass. The mass of a photon is its energy divided by c squared, or Plank's constant * frequency / c^2. Anything with energy has mass. Photons have no *rest* mass, but photons are never at rest anyway. As the previous poster noted, the flashlight does recoil. -- Rick Matthews matthews@wfunet.wfu.edu Ham radio: Wake Forest University 910-759-5340 (Voice) WA4GSP Winston-Salem, NC 27109-7507 910-759-6142 (FAX)
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X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 16cfd8,55863ecabe0590e3 X-Google-Attributes: gid16cfd8,public X-Google-ArrivalTime: 1994-05-03 07:48:47 PST Path: arc1-ca.pugleaf.net!bga.com!news.sprintlink.net!uunet!spool.mu.edu!howland.reston.ans.net!europa.eng.gtefsd.com!gatech!news-feed-2.peachnet.edu!concert!news.wfu.edu!ac!matthews From: matthews@ac.wfu.edu (Rick Matthews) Newsgroups: bit.listserv.physhare Subject: Re: questions about light Date: 2 May 1994 17:48:06 GMT Organization: Wake Forest University Lines: 27 Message-ID: <2q3ecm$frj@quad.wfunet.wfu.edu> References: <Pine.3.05.9404270835.B2036-a100000@calvin.stemnet.nf.ca> NNTP-Posting-Host: ac.wfunet.wfu.edu X-Newsreader: TIN [version 1.2 PL2]