Mass in special relativity (including the kinetic energy of the gas) only when it is measured in the center of momentum frame. Just as is the case for single particles, the calculated "rest mass" of such a container of gas does not change when it is in motion, although its "relativistic mass" does change. The container may even be subjected to a force which gives it an overall velocity, or else (equivalently) it may be viewed from an inertial frame in which it has an overall velocity (that is, technically, a frame in which its center of mass has a velocity). In this case,
Mercy Multiplied Francesca Battistelli. Mercy Multiplied Mercy Multiplied is an international, Christian and charitable organization that offers a six-month residential program for young women aged between 13 and 28 who struggle with various "life controlling" issues such as eating disorders, depression, self-harm, abuse issues, and drug and alcohol addictions. The ministry operates as A Girl Called Hope in New Zealand. Mercy Multiplied has a pro-life stance in their faith-based approach, and as such, extend their program to offer women with unplanned pregnancies with alternatives to abortion, as well as treat women who identify as lesbian or who have sexual identity issues. In