AeroPod, PowerPod and Newton

Thanks for the explanation. So kcal tells me how many Big Macs I need to eat to avoid losing weight and is just kjoules adjusted by an effeciency factor which is assumed to be 25%. That made me curious since it would seem that different activities would vary widely in effeciency, so I used Google an...

My physics book says that one Kcal is equal to 4.187 Kjoule, but in the iBike program one Kcal equals .956 Kjoule. What is the reason for the apparent discrepancy?