Question

According to Einstein’s theory of relativity, the mass m of a body moving with velocity v is

m
=
m
0
√
1
−
v
2
c
2
, where
m
0
is the initial mass and c is the speed of light. What happens to m as
v
→
c
−
. Why is a left hand limit necessary?

Answer 1

As
`v \to c^(-)`,
`m \to \infty` because the numerator is constant while the denominator approaches 0 from the positive direction.

The left hand limit is necessary because if
`v` were to approach
`c` from the right, the denominator wouldn't be defined over the reals.