Solved Examples on Unit of Speed
Example 1: The distance travelled by a body is 3 kms in 10 mins. Find its speed in SI units.
Solution:
The SI unit for speed is m/s.
Distance Travelled = 3 kms = 3 × 1000 meters = 3000 m
Time Taken = 10 mins = 10 × 60 secs = 600 s
Now, Speed = Distance/Time
⇒ Speed = 3000/600 = 5 m/s
Thus, speed in SI units for given case is 5 m/s.
Example 2: Which of the following is a unit of speed?
(a) mm × s (b) sec/m (c) cm/s (d) mins/m
Solution:
We know that,
Formula for speed is distance/time.
Thus, Option (c) is correct.
Example 3: A body travels 45 seconds with a speed of 4 m/s and 30 seconds with a speed of 5 m/s. Find the average speed for this journey.
Solution:
We know that,
Average Speed = (Total Distance Covered)/(Total Time Taken)
Here, Total time taken = (45 +30) s = 75 s
Distance travelled in first 45 seconds = 4 × 45 = 180 m
Distance travelled in later 30 seconds = 5 × 30 = 150 m
Total distance covered = 180+150 = 330 m
Average Speed = 330/75 = 4.4 m/s
Unit of Speed
Unit of Speed is meters per second or m/s. Speed is a physical quantity that measures the distance travelled by an entity per unit of time. The most commonly used units for speed are meters per second (m/s), kilometres per hour (km/h) and miles per hour (mph). Speed and Velocity are the same physical quantity except for the difference that velocity is a vector quantity and speed is a scalar quantity, so speed and velocity units are the same.
In this article, we will learn the definition of speed, the unit of speed, conversion between units in various systems, sample problems, and frequently asked questions related to the unit of speed.
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