Btu (I.T., pre-1956)
The Btu (I.T., pre-1956) refers to the International Table Btu, a specific definition used before 1956. It represents the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit at a constant pressure of one atmosphere.
Newton-meters
A newton-meter (Nm) is primarily used to quantify torque which is the rotational force applied to an object. It is the force of one newton applied perpendicularly to a lever arm one meter long.