Basics of Time, Speed and Distance
In this module we will learn about the basic concepts of Time, Speed and Distance.
Time, Speed and Distance Formula
Speed - distance covered by a moving object in unit time.
So, Speed = $\frac{Distance}{Time}$
Or we can write the above formula as follows:
Distance = Speed × Time
Q. What is the speed of a person who travels 20 km in 5 hours?
Explanation:
Speed = $\frac{Distance}{Time}$ = $\frac{20}{5}$ = 4 km/hour
It means that the person travels 4 km in one hour.
Units of Measurement of Time, Speed and Distance
Conversion of units of speeds:
- x km/hr = x × $\frac{5}{18}$ = $\frac{5x}{18}$ m/sec
- x m/sec = x × $\frac{18}{5}$ = $\frac{18x}{5}$ km/hr
(You can drive the above values if you put 1 km = 1000 m and 1 hour = 3600 seconds)
Every 18 kmph corresponds to 5 m/s.
Thus 36 kmph = 10 m/s, 54 kmph = 15 m/s and 72 kmph = 20 m/s.
Q. If a person can cross a 1200 metre long bridge in 10 minutes, then what is his speed in km per hour?
Explanations :
Time = 10 minutes = 10 × 60 = 600 seconds
Speed = $\frac{Distance}{Time}$ = $\frac{1200}{600}$ = 2 m/sec
x m/sec = x × $\frac{18}{5}$ = $\frac{18x}{5}$ km/hr = $\frac{36}{5}$ km/hr = 7.2 km/hr
Time = 10 minutes = 10 / 60 = 1/6 hour
Distance = 1200 metre = $\frac{1200}{1000}$ = 1.2 km
Speed = $\frac{Distance}{Time}$ = $\frac{1.2}{(1/6)}$ = 7.2 km/hr
Other Formulae
Formula 1
Formula for finding out the number of revolutions:
Distance, D = Circumference × n = 2πrn
Where, n = number of revolutions and r = Radius of circle
Formula 2
Formula for finding the distance based on the count of the number of poles (e.g. when you are travelling in a train):
Total distance = (n - 1)x
Where, n = number of poles and x = Distance between consecutive poles.