Time (Speed, Distance and Time)
Ria reaches her school in 10 minutes whereas her friend
Dia takes 15 minutes to reach. This mean Ria takes lesser time than her friend
Dia to reach school.
In the above, the word ‘time’ has been used. Time is
measured in seconds, minutes and hours.
When distance and speed are given in the question we measure
time in the following way.
Illustration 1: How
much time will be taken to cover a distance of 100 km at a speed of 10 km per
Solution: Time taken to cover 10 km = 1hr.
taken to cover 1 km = 1/10 hrs.
taken to cover 100km = 1/10 x 100 = 10 hrs.
Illustration 2: A car covers a distance of
150 km at a speed of 50 km/hour. Find the time taken to cover this distance.
Solution: Time = distance/speed
Time = 150 km/(50 km/hour)
= 3 hours.
Illustration 3: A motor cyclist covers a
distance of 20 km at a speed of 10km per hour. Calculate the time taken to
cover this distance.
Solution: Speed = 10 km/hour
Distance covered = 20 km
Time = distance/speed
Illustration 4: A boy runs at a speed of
20 m per minute. How much time will be taken to cover a distance of 1km?
Solution: 20 m is covered in 1 min
1 m is covered in 1/20 min
1000 m (i.e. 1km) is covered in 1/20 x 1000 = 50 min