A physical quantity is defined as mass per unit volume why

Along wire of diameter 1 mm is submerged in an oil bath of temperature ∞ 31°c. the wire has an electrical resistance per unit length of 0.01 ω/m. if a current of 103 a flows through the wire and the convection coefficient is 500 w/m2·k, what is the steady-state temperature of the wire? from the time the current is applied, how long does it take for the wire to reach a temperature that is within 1°c of the steady-state value? the properties of the wire are 8000 kg/m3, 500 j/kg·k, and 20 w/m·k.

Cho is making a bar graph showing the amount of money spent on health care between 1999 and 2005. the dependent variable is the: a: money spent b: year c: number of patients

Which if these is an etiquette rule? (american football) question 10 options: a. debating with the ref over a call b. not communicating with your team c. post-game handshake d. taunting