Determine whether a scalar or a vector is described in (a) and (b). Explain your answers.
(a) A ballistics test shows that a bullet hit a wall at a speed of $400 \mathrm{ft} / \mathrm{s}$
(b) A ballistics test shows that a bullet hit a wall at a speed of $400 \mathrm{ft} / \mathrm{s}$ perpendicular to the wall.