Question

Which is a valid velocity reading for an object?

45 m/s
45 m/s north
0 m/s south
0 m/s

Answer 1

Velocity is a vector (magnitude + direction). So "45 m/s north" is valid. For zero speed the direction is meaningless, so "0 m/s" is valid but "0 m/s south" is not. Thus valid: 45 m/s north and 0 m/s.