Telll what this symbol represent​

The slope of a velocity time graph over any interval of time gives the during that interval

When is a current produced? when the terminals of an electrochemical cell are connected by a wire if the electric circuit is opened in an electrochemical cell if the electrolyte is removed from an electrochemical cell when the electrodes are reversed in an electrochemical cell

What is the increase in density of a medium due to wave travel?