Which of the following conditions must be met to have electric current flow through a circuit?
The circuit must be a closed loop.
The circuit must have a source of electric charges (energy).
A potential difference through the circuit must exist.
All of the above conditions are necessary for electric current flow.

The man of mass m1 and the woman of mass m2 are standing on opposite ends of the platform of mass m0 which moves with negligible friction and is initially at rest with s = 0. the man and woman begin to approach each other. derive an expression for the displacement s of the platform when the two meet in terms of the displacement x1 of the man relative to the platform.

Which statement is the best definition of an atom? a) anything that has mass and occupies space. b) the smallest particle that has the properties of an element. c) a substance that cannot be broken down chemically into simpler substances. eliminate d) the smallest unit of a substance that exhibits all of the properties characteristic of that substance.

When barack obama was running for president, at a campaign stop he tried to bowl, something he isn't very good at. the media loved it because he threw a gutter ball while they were all watching. this is an example of: