Measurement of Speed: Definition, Units, & Applications

Measurement of the speed of how fast we travel can really help us in saving our time. Speedometers are used for the measurement of speed in vehicles. To measure the distance covered, odometers are useful. Speed can also be calculated with the help of a graph. Measuring the speed in advance and before the journey will assist you in formulating a schedule that will be time-efficient. 

Read Also: Derivation of Equation of Motion

Key Terms: Speed, Velocity, average speed, relative speed, instantaneous speed, uniform speed, non-uniform speed, variable speed

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What is Speed?

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The pace at which an entity or an object's placement changes in any direction is called speed. Speed can be explained as the ratio of distance traveled to the time it took to move from one point to another and cover that distance. Because speed has just one direction and no magnitude, it is a scalar number.

As a result, the speed equation is as follows:

s = d/t

Where, The speed in m.s^-1 is denoted by s.

The symbol d is used to denote the distance traveled by the body in meters.

t is the amount of time spent in s.

Distance, Speed, and Time Relation

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Units of Speed

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The measurement of speed is measured in meters per second (m/s). The unit of speed in the CGS (Centi-Gram-Second) system is cm/s. The procedures for determining the dimensional formula for speed are as follows:

T = Time’s dimensional formula

L = Distance’s dimensional formula in meter

The equation of speed is based on the distance covered per unit of time, hence, the dimensional speed formula is [LT^-1].

Read More: Uniform Acceleration

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Different kinds of Speed

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There are different kinds of speeds are as follows:

• Variable speed
• Uniform speed
• Average speed
• Relative Speed
• Instantaneous speed

Speed is a scalar quantity. It does not indicate the body’s direction; however, it does indicate the magnitude.

Uniform Speed

If an item travels the same distance in the same amount of time, we can say that the body is traveling at a uniform speed, regardless of how short the periods are.

Uniform Speed

Non-Uniform Speed or Variable Speed

When a body travels in irregular lengths or time intervals, the object is stated to move at different speeds. A car's speed is considered to be non-uniform.

Non-Uniform Speed

Check Also: Average Velocity Formula

Average Speed

While an item moves at a non-uniform pace, the average speed is the constant speed at which it travels the same magnitude of distance in the same time interval as it does when traveling at a continuously varying speed. As a result, we define average speed as the fraction of the vehicle's total distance traveled to the entire time taken.

Average speed is calculated by multiplying the overall distance covered by the entire time spent.

If a vehicle travels at distinct speeds (v1, v2, v3) and at uneven time intervals (t1, t2, t3), then,

As a result, the average speed calculated will be: (v1t1 + v2t2 + v3t3)/(t1 + t2 +t3)

Assuming that the time intervals are identical, the formula becomes: t1 = t2 = t3 = n.

v = (v1+v2+v3)/n

The average speed in this situation is the arithmetic average of all the speeds.

Average Speed

Read Further: Average Speed Formula

Instantaneous Speed

An item travels the same distance at uneven time intervals. The idea of instantaneous speed may be used to determine various speeds at different times. 

Let's say an item travels a distance of s in a short period t. Thus, the instantaneous speed is calculated as follows: Instantaneous speed = limΔt → 0 Δs/Δt

If the 1^st derivative of the given equation is found, the equation is rewritten as:

= limΔt→0 (ds/dt)

It's important to remember that the instantaneous speed equals the uniform speed with uniform motion.

Instantaneous Speed

Check Further: Speed Distance Time Formula

Relative Speed

If two objects move in the same direction, their speeds are summed, i.e., v_REV = v1 + v2.

If they are traveling together in the direction, the difference in their speeds is the relative speed, i.e.

v_REV = v1 - v2

Relative Speed

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Applications of Speed

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In our daily lives, we watch the movement of human beings, animals like cats and dogs, motor vehicles, turbine spinning, and many other items, all of which have a speed connected with them, allowing them to traverse a specific distance in a given period of time.

The pace at which anybody travels some distance in some period of time is referred to as speed. However, it is possible to calculate the distance traveled or the speed at which a car or other vehicle may traverse a certain distance.

Also Read: Displacement Formula

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Measurement of Speed

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Speedometers are used to measure the speed of vehicles. Odometers track the distance traveled by the vehicle. A graph can help in calculating the speed as well like the distance-time graph. It aids in determining an object's speed. Some instrument that helps in the measurement of speed are as follows –

Speedometers

Traveling speed of land vehicles is measured via speedometers. They're utilized to assist drivers in determining their driving speed and keeping it safe and realistic. The pace of travel is determined by magnets and a series of rotating wires attached to the transmission, which is displayed on an analog screen on the vehicle's panel.

Speedometer

Tachometers

The motor speed is measured in revolutions per minute using tachometers (rpm). This device measures the rotational speed and shows the result on an analog dial screen on the dash of a car or any other vehicle. The rpm range shown by the display is a safe range, which is intended to assist the driver in determining the appropriate gear settings, as well as the proper cruising speeds.

Tachometers

Check More: Difference between Kinetics and Kinematics

Accelerometers

Accelerometers are used to assess a vehicle's acceleration and deceleration rates to see if the drive brake and train systems are working properly. This device is used to demonstrate a vehicle's engine power by displaying how fast it can go from zero to sixty miles per hour. They may come in handy in tracking animals from afar.

Accelerometers

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Things to Remember

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• Speed can be explained as the ratio of distance traveled to the time it took to move from one point to another and cover that distance.
• It is calculated by dividing distance by time.
• m/s is the SI unit of speed.
• Distance – time graph can a used to calculate the speed of anybody.
• Speed tells only the magnitude.
• Speed does not give any information about the direction of the body.
• Speedometers are used to measure the speed of vehicles. 
• Odometers track the distance traveled by the vehicle.

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