Which of the following is an example of a velocity? o a. 12 m/s o b. 45 km/hr south o c. 55 km/hr d. -5 m/s2 east

B. 45 km/hr south

Explanation:

Velocity is a vector quantity which consists of:

- A magnitude, given by the ratio between displacement and time taken for the motion

- A direction, which corresponds to the direction of the displacement

Let's analyze now each option:

A. 12 m/s --> this is not a velocity: this is a speed, because it does not specify the direction, so it is only a scalar quantity

45 km/hr south --> this is a velocity, because it specificies both magnitude (45 km/h) and direction (south)

C. 55 km/hr  --> again ,this is not a velocity, but it is a speed, because it does not specify the direction, so it is only a scalar quantity

D. -5 m/s2 east --> this is not a velocity, but it is an acceleration, since the units of measurement are the ones of acceleration (m/s^2, while for the velocity should be m/s or km/h)

54 degrees incident angle = reflected angle

angle is from normal turned to line of ray