How much work is done if a machine exerts 850 watts of power in 30 seconds

When you turn on a battery-operated device, an electrical circuit is

Which best describes the weak nuclear force? it maintains attraction between the m ecules in liquids. it attracts the nucleus of one atom to the nucleus of another atom. it pulls all matter in the universe together it keeps particles that make up protons and neutrons together

The stopwatch used by a student to measure velocity of a pulse in a slinky was of least count 0.1 second. he stops the stopwatch when a pulse has made 3 journeys from one end to the other of the slinky. he finds the seconds hand to be at 52nd division. calculate the correct time noted by him.