1. The problem statement, all variables and given/known data can somebody help my figure out what t0 l0 l and t is? For instance: A girl an her dad are in an airplane, the girl starts running 20m in 8 seconds. There is also a boy standing beneath the plane (lets pretend that the airplanes floor is seethrough. 2. Relevant equations 3. The attempt at a solution What is the thumb rule here? I thought that the boy is t0 because he is standing still. The boy is also l0 because he is not moving. The girl is l cuz she is in motion and the dad is t cuz he is taking the time and he is not moving. I got a key from my teacher and this is totally wrong... Help me sort this out?