# Clarification in the definition of force

1. Sep 4, 2013

### manimaran1605

\According to Newton's second law, force is defined as rate of change of momentum or force is defined as product of mass into acceleration, I both of these definitions are same and right.

My questions are,
(1) how can i prove this two definitions are same?

2. Sep 4, 2013

### zhangwfjh

F=dp/dt=d(mv)/dt=m(dv/dt)=ma
Actually, these two definitions are not equivalent in the framework of special relativity.