Question

A and B start from the same place, in the same direction and at the same time with the speeds 6kmph and 2m/sec respectively. After 5 hours who will be ahead and by how much?

Answer 1

The values of their respective speeds are given in kmph and m\sec. So first of all we have to convert them into the same quantity. To convert km/h into m\sec we have to multiply it with 1000/3600. This is because 1km=1000m and 1hr=3600sec.

Complete step by step answer:
First of all we have to convert km/h into m\sec. So, 6kmph is equal to $6 \times {{1000} \over {3600}} = 6 \times {5 \over {18}} = {5 \over 3} = 1.66$. i.e. the value of 6kmph =1.66m\sec.
Distance covered by A=$1.66 \times 5 \times 3600 = 30km$ and distance covered by B=$2 \times 5 \times 3600 = 36km$.
It is clear that B will be ahead of A by 6km.To compare the speed or any other quantity we have to bring them in the same units. This makes it easier to compare the values. The speed of A is given in kmph that means it gives the measure of distance in kilometer and the time in hours. The speed of B is given in m\sec which means it gives the measure of distance in meter and time in seconds.

Since the speed of B is more than that of A so B will cover more distance than A. This makes it quite difficult to compare their speeds. So it is better to convert km/h into m\sec or m\s to km/h. Speed is defined as the total distance covered in unit time. When the body is in motion, speed is one of the most important properties.

Note: From the given values it is seen that A has more speed But their units are not the same. So firstly we have to make the units the same. After converting it is seen that 2m\sec is greater than 6kmph. So B will cover more distance than A by 6km.