Question

The units of speed and average speed are
A. same across all systems of units
B. same only for SI
C. different across all systems of units
D. different only for SI

Answer 1

Hint: Recall the definitions of the speed and average speed of an object. From these definitions of speed and average speed of an object, determine the physical quantities involved in the definition. From the units of these fundamental physical quantities, determine the units of speed and average speed of an object.

Complete answer:
The speed of an object is the total distance travelled by an object in a time interval.
The average speed of an object is the ratio of the distance travelled by the object to the elapsed time interval for the travel.
From the definitions of both speed and average speed of an object, it can determine that both of these speeds involve the ratio of length to time.
Hence, the SI unit of speed and average speed is meter per second.
Therefore, in any system of units, the unit of speed and average speed will be the same as it is the ratio of distance and time.

So, the correct answer is “Option A”.

Additional Information:
The speed of an object is a scalar physical quantity which means that the speed of an object has magnitude but not direction.
The unit of speed and average speed in the CGS system is centimeter per second.

Note:
One can also solve the same question in another way. One can give the units of speed and average speed in some of the most commonly used systems of units like SI system, CGS system, FPS system, etc and show that the units of these two physical quantities are the same in all used systems of units.