0
votes
2answers
46 views

Calories Burned While Hiking [closed]

I want to find out how many calories are burned on any particular hike by any particular by using a formula. I figure it's probably a simple physics question, but since I never took physics, I don't ...
2
votes
1answer
187 views

Can non-free forces change the rest mass?

While reading Hobsen et al.'s "General Relativity: An Introduction for Physicists", I came across a bit confusing derivation. Multiplying the 4-force and 4-velocity, the following derivation can be ...