1. The problem statement, all variables and given/known data I would appreciate feedback on the following two problems: (1) For a given operator A with no explicit time dependence I am asked to show that d/dt(eAt)=A(eAt) (2) A free wave packet of width Δx is traveling at a constant velocity v0=p0/m. I am asked to estimate the time-energy uncertainty relation. 2. Relevant equations 3. The attempt at a solution (1) Is this as straightforward as it appears to be? Probably isn't, right? Is this to be solved using Ehrenfest's theorem? Or how? (2) I can easily show that ΔEΔt ~ ħ but is this what I am plainly asked, or am I rather asked to arrive at a more exact result (i.e. find the proportionality coefficient)?