What is thermal energy?
a. thermal energy is a measure of a substance specific heat
b. thermal energy is the measure of movement of the substances molecules
c. thermal energy is the same as the substances temperature
d. thermal energy is measure of a substance vaporization

An astronaut in space cannot use a scale or balance to weigh objects because there is no gravity. but she does have devices to measure distance and time accurately. she knows her own mass is 77.4 kg , but she is unsure of the mass of a large gas canister in the airless rocket. when this canister is approaching her at 3.50 m/s , she pushes against it, which slows it down to 1.30 m/s (but does not reverse it) and gives her a speed of 2.60 m/s . what is the mass of the canister?