Exercise 12 (B) Question 5 - Selina Mathematic Class 6 – Idea of Speed, ...

Problem 5: Which is greater: a speed of 45 km/h or speed of 12.25 m/sec?

                           How much is the distance traveled by each in 2 seconds? 

Problem 5: Which is greater: a speed of 45 km/h or speed of 12.25 m/sec?

                           How much is the distance traveled by each in 2 seconds?

Given

First speed =45 km/h

Second speed =12.25 m/sec

=[(1225×60×60)/(100×1000)]km/h

=(1225×6×6)/1000km/h

On further calculation, we get

=(49×6×6)/40km/h

=(49×3×3)/10km/h

We get,

=441/10km/h

=44.1km/h

Hence, it is clear that the first speed 45 km/h is greater than the second speed 12.25 m/sec

Now, the distance travelled in 2 seconds at 45 km/h is shown below

Speed =45km/h

=(45×1000)/(60×60)m/sec

We get,

=450/36m/sec

Time=2sec

Hence,

Distance=450/36m/sec×2sec

=450/18m

=25m

Now, the distance travelled in 2 seconds at 12.25 m/sec is shown below

Speed =12.25m/sec

Time=2sec

Hence,

Distance=12.25m/sec×2sec

=24.50m

Therefore, the distance traveled by each in 2 seconds is 25 m and 24.50 m