# Conversion of Units of Speed

Here we will learn the conversion of units of speed

(i) Conversion of km/hr into m/sec

(ii) Conversion of m/sec to km/hr

How to convert km/hr into m/sec?

km/hr = 1 km/1 hr = 1 × 1000 m/60 × 60 sec = 1000/3600 m/sec = 5/18 m/sec

So, we say that to convert km/hr into m/sec, we multiply by 5/18.

Solved examples on conversion of km/hr into m/sec:

1. Convert 72 km/hr to m/sec

Solution:

72 km/hr

= 72 × 5/18 m/sec

= 20 m/sec

2. The speed of the bicycle is 90 km/hr, what is its speed in m/sec?

Solution:

Speed of bicycle = 90 km/hr

To convert the speed into m/sec, we multiply by 5/18

Therefore, speed of bicycle = 90 × 5/18 m/sec = 25 m/sec

3. A car covers a distance of 100 km in first two hours, 120 km in next 1 hour and 32 km in next 1/2 hour. Convert the speed into m/sec.

Solution:

Total distance covered by the car = (100 + 120 + 32) km = 252km

Total time taken = (2 + 1 + 1/2) hr = (4 + 2 + 1)/2 = 7/2 hr

Therefore, average speed = Distance covered/Time taken

= 252 km/(7/2) hr

= 252/1 × 2/7 km/hr

= 72 km/hr

To convert the speed into m/sec, we multiply by 5/18

Therefore, 72 km/hr = 72 × 5/18 = 20 m/sec

How to convert m/sec to km/hr?

m/sec = 1m/1sec = (1/1000) km/(1/60 × 60) hr = 60 × 60 /1000 km/hr = 18/5 km/hr

So, we say that to convert m/sec into km/hr, we multiply by 18/5

Solved examples on conversion of km/hr into m/sec:

1. Convert 40 m/sec to km/hr

Solution:

40m/sec

= 40 × 18/5

= 144 km/hr

2. The speed of a cyclist is 4 m/sec. find the speed in km/hr.

Solution:

Speed of a cyclist = 4 m/sec

To convert the speed in km/hr, we multiply by 18/5

Therefore, speed of the cyclist = 4 × 18/5 km/hr

= 72/5 km/hr

= 14.4 km/hr

Hence, we have learnt the conversion of units of speed from km/hr to m/sec and m/sec to km/hr.

Speed of Train

Relationship between Speed, Distance and Time

Conversion of Units of Speed

Problems on Calculating Speed

Problems on Calculating Distance

Problems on Calculating Time

Two Objects Move in Same Direction

Two Objects Move in Opposite Direction

Train Passes a Moving Object in the Opposite Direction

Train Passes through a Pole

Train Passes through a Bridge

Two Trains Passes in the Same Direction

Two Trains Passes in the Opposite Direction