Week 6 Energy, Momentum & Conservation of Energy

Question 1

what are the Newtonian equations for momentum and kinetic energy and what is their problem under Lorentz transformations

Answer 1

p = mv
E = 1/2mv^2
they are not invariant under Lorentz transformations

Question 2

why can we not use Newtonian momentum and kinetic energy equations for inertial reference frames

Answer 2

they are not invariant which contradicts the idea hat energy and momentum are always conserved which are laws of physics that must be obeyed in inertial reference frames

Question 3

give the 4D momentum and energy equations

Answer 3

P = γmv
E = γmc^2

Question 4

what is the invariant mass equation

Answer 4

E^2 = c^2p^2 + m^2c^4

Question 5

when is the E = mc^2 + 1/2mv^2 energy conservation equation used

Answer 5

only when v &laquo_space;c

Question 6

how does energy conservation work in relativity

Answer 6

only total energy is conserved