# Differentiating Lorentz factor with respect to time

1. Jan 29, 2007

### anantchowdhary

1. The problem statement, all variables and given/known data
I would like some help on differentiating the lorentz factor with respect to time

2. Relevant equations

3. The attempt at a solution

i arrived at $$(-1/2) (1-v^2/c^2)^{-3/2}$$
but a forum on this website says it is $$(-1/2) (1-v^2/c^2)^{-3/2} ( \frac{-2v}{c^2} dv/dt)$$

2. Jan 29, 2007

### cristo

Staff Emeritus
You want $$\frac{d}{dt}(1-v^2/c^2)^{-1/2}$$. Using the chain rule, this is equal to $$\frac{d}{dv}(1-v^2/c^2)^{-1/2}\frac{dv}{dt}=\left(\frac{-1}{2}\right)\left(\frac{-2v}{c^2}\right)(1-v^2/c^2)^{-3/2}\frac{dv}{dt}$$

Does that help?

3. Jan 29, 2007

### anantchowdhary

Thnx a ton cristo!Just cudnt think about it