# Missing v?

for the following question:
dynamite liberates about 5.4*10^6 J/kg when it explodes. What fraction of its total energy content is this?

my problem:
the total energy formula=(gamma)mc^2
but the gamma factor has v, but the question doesn't have v...
any suggestions?

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Tom Mattson
Staff Emeritus
Gold Member
Assume that the dynamite is at rest.

if it explodes, it shouldn't be at rest, right?

Tom Mattson
Staff Emeritus
Gold Member
If the stick of dynamite is at rest prior to the explosion, then its center of mass will surely be at rest afterwards. Also, the total energy is the same before and after the explosion.

So what would you rather do? Would you rather calculate the energy content after the explosion, including the kinetic energy of each individual fragment? Or would you rather calculate the total energy of a stationary stick of dynamite whose mass is known?

asdf1 said:
if it explodes, it shouldn't be at rest, right? Why not?

Astronuc
Staff Emeritus