> incompatible quantities have incompatible units Okay; how do you add the unit of energy, one joule, to the unit of torque, one newton-metre? Both have the s

> incompatible quantities have incompatible units Okay; how do you add the unit of energy, one joule, to the unit of torque, one newton-metre? Both have the same SI units: kilogram square metre per second per second. But one is a scalar quantity, whereas the other is a vector quantity.