The Trek BBS statistics

Posts: 5,404,993
Members: 24,760
Currently online: 574

Retro Review: Time’s Orphan
By: Michelle on Aug 30

September-October Trek Conventions And Appearances
By: T'Bonz on Aug 29

Lee Passes
By: T'Bonz on Aug 29

Trek Merchandise Sale
By: T'Bonz on Aug 28

Star Trek #39 Villain Revealed
By: T'Bonz on Aug 28

Trek Big Bang Figures
By: T'Bonz on Aug 28

Star Trek Seekers Cover Art
By: T'Bonz on Aug 27

Fan Film Axanar Kickstarter Success
By: T'Bonz on Aug 27

Two New Starship Collection Ships
By: T'Bonz on Aug 26

Trek Actor Wins Emmy
By: T'Bonz on Aug 26

 The Trek BBS Confused about E=mc²
 User Name Remember Me? Password
 Join Us FAQ Members List Social Groups Calendar Mark Forums Read

 Science and Technology "Somewhere, something incredible is waiting to be known." - Carl Sagan.

 July 18 2013, 11:32 PM #1 Lt. Uhura-Brown Lieutenant Commander   Location: New Zealand Confused about E=mc² I was thinking about the famous equation E=mc² the other day, when I realised I didn't actually understand it, or rather, the units used. It seems to me that Joules = (volume multiplied by density) multiplied by (300 million meters divided by 1 second) multiplied by (300 million meters divided by 1 second)? I know there's something I must be missing, but I can't wrap my head around how it all fits together.
 July 19 2013, 12:47 AM #2 Christopher Writer Re: Confused about E=mc² Mass is a basic quantity that doesn't have to be broken down; kilograms are generally the preferred unit. A joule is a newton-meter, and a newton is a kilogram-meter per second squared; so that means joules are (kg x m/s^2) x m = kg x m^2/s^2 = kg x (m/s)^2, which is mass (kg) times velocity (m/s) squared, with the velocity being the speed of light. So a mass of 1 kg, if converted to energy, would come out to 1 kg x (3 x 10^8 m/s)^2 = 9 x 10^16 J. __________________ Christopher L. Bennett Homepage -- Site update 4/8/14 including annotations for Rise of the Federation: Tower of Babel Written Worlds -- My blog
 July 19 2013, 08:04 AM #3 Asbo Zaprudder Rear Admiral     Location: Sand in the Vaseline Re: Confused about E=mc² ^What Christopher says. Also, in particle physics and astrophysics, the units commonly used are electron volts (eV) for energy and eV/c² for mass -- the latter usually being abbreviated to eV if natural units are used which set c=1. One volt (V) is defined as being the potential difference when one coulomb (C) of charge crosses that potential resulting in a change of one joule (J) of energy. One electron volt is defined as the magnitude of the energy change of an electron moving through an potential difference of one volt. So 1 eV = 1.602x10^−19 J given that the magnitude of the charge on the electron is 1.602×10^−19 C (the charge is actually a negative quantity for electrons and positive for positrons, of course). __________________ "After a time, you may find that having is not so pleasing a thing, after all, as wanting. It is not logical, but it is often true." -- Spock -- Flip flap! Last edited by Asbo Zaprudder; July 19 2013 at 08:22 AM.

 Bookmarks