Define New Unit and Rewrite Unit

Load the collection of symbolic units by usingsymunit. Find information on the predefined unitu.c_0光的速度。

u = symunit; unitInfo(u.c_0)

speed of light in vacuum - a physical unit of velocity. Get all units for measuring 'Velocity' by calling unitInfo('Velocity').

Show that the exact value of the speed of light in SI is299792458metres per second.

c = unitConvert(u.c_0,'SI')

c = 299792458*([m]/[s])

Define the new unitspeedOfLightApproxfor the approximate value of the speed of light as3e8meters per second.

u = symunit; c = newUnit('speedOfLightApprox',3e8*u.m/u.s)

c = [speedOfLightApprox]

Alternatively, you can specify the unit by usingu.speedOfLightApprox.

Define the equationE=mc²using the new unit.

syms mass m = mass*u.kg; E = m*c^2

E = mass*[kg]*[speedOfLightApprox]^2

RewriteEin terms of meters per second.

E = rewrite(E,u.m/u.s)

E = 90000000000000000*mass*(([kg]*[m]^2)/[s]^2)

Since the standard unit of energy is the joule, rewriteEin terms ofJoule.

E = rewrite(E,u.Joule)

E = 90000000000000000*mass*[J]