The scalar quantities include most of the thermodynamic state variables involved with the propulsion system such as the density pressure and temperature of the propellants. The direction of a vector can be described as being up or down or right or left. Pin On Creative Classroom Vectors have magnitude and direction scalars only have magnitude. . We have an expression for the energy density that is the sum of an electric energy density and a magnetic energy density whose forms are just like the ones we found in statics when we worked out the energy in terms of the fields. The scalar changes the size of the vector. Scalar and vector quantities are treated. A Possible Scalar Term Describing Energy Density in the Gravitational Field. On the other hand a vector quantity is. Multiplication of a vector by a scalar is distributive. A vector is often written in bold like a or b so we know it is not a scalar. Scalar