Question

What is the time taken by a boy running at a speed of 20 km/hr to cover a distance 400 meter?

Answer 1

Answer:First u need to convert the speed of boy from km/hr to m/s

So,

1 km = 1000 m

And, 1hour=3600 seconds.

So, 1 km /hr= 1000/3600

= 5/18 m/sec.

So, 20 km/ hr= 20×5/18 =100/18 m/s.

The distance is given 400 m. And we meet to find Time as given-

Now, put the formula-

Speed (velocity) = Distance/Time

100/18 = 400/Time

Rearranging,

Then, Time =Distance/speed

=400/ (100/18)

= 400×18/100

= 4×18

= 72 seconds.

Explanation: