Measurement of Speed
Speed isn’t only about numbers; it’s a change in movement itself. Like other measurable quantity speed also has its advantages. So, join us on the journey to uncover the hidden art of measuring speed.
Further in this article, we will learn about the statement, formula, its dimensional formula, various types, measurement of speed, various instruments for measurement of speed, velocity, and difference between velocity and speed. Additionally, there will be a few practice problems for better understanding and clarification.
What is Speed?
Speed is a fundamental concept in physics, and is given by,
The rate of change of an object in any direction.
Speed is a scalar quantity; hence no direction only magnitude is present.
Speed Definition
Speed has only magnitude, its the rate of motion without any direction. It’s a scalar quantity. It is measured in units like meters per second (m/s) or kilometers per hour (km/h).
Speed Formula
The formula of speed is given by,
Speed = D/T
where,
- D is the Distance Traveled
- T is the Time Taken
Its units is given by,
- In CGS system cm.s-1
- In SI system m.s-1
Dimensional Formula of Speed
As we know spped is given by distance divided by time its dimensional formula is given as,
Dimensional Formula of Speed = [M0L1T-1]
Types of Speed
Different types of speed are:
- Uniform Speed
- Variable Speed
- Average Speed
- Instantaneous Speed
- Relative Speed
Let’s learn about them in brief.
Uniform Speed
Constant rate of motion without any change in velocity.
vuniform = Total Distance/Total Time
For example: A car cruzing at 80 kmph on a highway.
Variable Speed
Motion of an object that changes pace or rate over time.
vvariable = Change in Distance/Change in Time
For example: A car moving from point A to B cruzing and taking multiple stops.
Average Speed
The total distance traveled divided by the total time taken.
vavg = Total Distance/Total Time
For example, speed of car in moving form point A to B.
Instantaneous Speed
The speed of an object at a particular moment in time.
v = limΔt→0 Δd/Δt
For example, speed of accelerating car.
Relative Speed
The speed of an object observed from another moving object.
vrelative = v1 ∓ v2
(plus when moving in same direction, minus when moving in opposite direction)
For example, spped of car with respect to a moving bicyle.
What is Measurement of Speed?
Speed is rate of change of any object, not just movement. There are various speed measuring devices which calculate different aspect of speed for instance Speedometers measure vehicle speed, odometers track distance, and graphs illustrate motion. However, speed’s definition varies based on context.
For example, in melting ice, it’s the rate of transformation, not motion. Similarly, a ‘slow’ laptop refers to processing efficiency, not physical speed.
Measurement of Speed of Light
Speed of light, denoted by “c,” which is approximately 299,792,458 meter/second, it serves as the limit for energy, matter, and information transmission in space.
Ole Romer’s 1676 observations of Jupiter’s moon marked as the first indication of light speed. Then Albert Einstein’s 1905 theory of relativity made c as a universal constant.
Measurement of Speed of Sound
Sound’s speed, is the distance a sound wave travels per unit time. At 20℃, sound travels at around 343 meter/second in air. The speed varies with the medium, being slowest in gases, faster in liquids, and fastest in solids.
The speed of sound, plays a vital part in fields like meteorology, affecting weather forecasting and various applications.
Measurement of Speed of Wind
Wind speed measures the movement of air from low to high pressure zones. Anemometers, instruments designed for this purpose, which quantify wind speed. Wind speed impacts all the aspects of nature by affecting weather forecasting, aviation, maritime operations, and ultimately influencing plant biology. Understanding wind speed is very important for the advancement of applications and better prediction atmospheric conditions.
Measurement of Speed Instruments
Various instruments used to measure the spped are,
- Speedometer
- Tachometer
- Accelerometer
Speedometer: A speedometer is a device which measures the vehicle speed in kilometers per hour or miles per hour.
Tachometer: A tachometer is a device which measure the working speed of an engine in revolutions per minute(RPM).
Accelerometer: An accelerometer is a device which measure the acceleration of a moving body.
What is Velocity?
Velocity is defined as,
The rate at which an object’s position changes with respect to time in specific direction is called velocity
Velocity is a vector quantity hence both direction and magnitude is present.
Formula of velocity is given by,
Velocity = Change in Displacement/Change in Time
Difference between Speed and Velocity
The general differnce between speed and velocity is added in the table below as,
Speed Vs Velocity |
||
---|---|---|
Characteristic |
Speed |
Velocity |
Definition |
Distance traveled by an object over time. |
Change in distance in a specific direction over time. |
Quantity Type |
Scalar quantity |
Vector quantity |
Example |
60 km/hour |
60 km/hour East |
Real-life Scenario |
Running on a treadmill at constant speed. |
Driving a car with changes in speed and direction. |
Conclusion
By understanding the speed of an object, from its definitions to various types, it become important in understanding the motion of objects. Whether knowing the instantaneous speed of an object or calculating the overall distance of a journey, speed helps us. And helps us in our understanding the concept of velocity and motion.
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Examples Measurement of Speed
Some examples on measurement of speed are,
Example 1. A car travels a distance of 150 kilometers in 2.5 hours. Calculate its average speed.
Solution:
Average Speed =Total Distance/Total Time
Average Speed = 150 km / 2.5 hours
Average Speed = 60 km/hour
Example 2. An athlete runs a 100-meter race in 10 seconds. Determine the athlete’s speed.
Solution:
Speed = Time/Distance
Speed = 100 meters / 10 seconds
Speed = 10m/s
Example 3. A sprinter accelerates from rest to a speed of 8 m/s in 4 seconds. Calculate the sprinter’s acceleration.
Solution:
Acceleration = Change in Velocity / Time
Acceleration = (8 m/s − 0) / 4 s
Acceleration = 2m/s2
Measurement of Speed FAQs
What is Speed?
Its the ratio of the distance travelled in the given time.
How to Measure the Speed?
It can be measured by its formula,
Speed = Distance/Time
What Unit of Speed?
The unit of speed is m.s-1
How is Speed Measured in Vehicles?
Speedometers in vehicles measure speed.
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