A particle has a lifetime of 2x10^-23 s. If the mass of the particle is measured when the particle is at rest in a potential free region, what is the minimum uncertainty in the mass measurement in MeV?

Asun-sized star will spend most of its lifetime as a: white dwarf red giant protostar main-sequence star

Apulley system is used to lift a 2,000 newton engine up a distance of 3 meters. the operator must apply a force of 250 newtons to the chain of the pulley system to lift the motor. to lift the engine 3 meters, the operator must pull a total of 30 meters of chain through the pulley system. what is the value of di?

Atruck travels at an average speed of 70 km/hr. if it travels 100 km in the first hour, how far will it go the second hour of a 2 hour trip? if you could also give me the steps that would great.