When lifting weights, arch your lower back for extra strength. Is this true?

While standing outdoors one evening, you are exposed to the following four types of electromagnetic radiation: yellow light from a sodium street lamp, radio waves from an am radio station, radio waves from an fm radio station, and microwaves from an antenna of a communications system. rank these type of waves in terms of increasing photon energy.

In a good thermo flask the main cause of heat loss is

Matter is needed to transfer thermal energy bya. conductionb. convectionc. radiation d. both a & b.