Question

a bus is moving at 20 ms .How much distance in kilometers will the bus cover in 25 mins

Answer 1

All this is based on the formula for speed, which is speed = distance / time. The problem gives you speed and time, and asks you to solve for distance, which would be distance = speed * time.

Before we can use that equation though, we need to convert the speed from m/s to km/m. You could do this in one step, but here we'll just split it into two steps to see it clearly.

The first parenthesis is the number we want to convert, the second is the conversion factor. For this first conversion, the first parenthesis is the given speed (20 m/s) and the second is the conversion for time, because 60 seconds is the same as a minute. Since seconds are in the denominator for the speed, we place seconds in the numerator of the conversion factor, so that when we multiply these units cancel out and we are left with our answer in meters / minute:

(20 meters / 1 second) * ( 60 seconds / 1 minute) = 20 meters / minute * 60 = 1200 meters / minute

We can now do the same, but this time converting meters to kilometers. The process is still the same as above with the time.

(1200 meters / minute) * ( 1 km / 1000 meters) = 1.2 kilometers / minute

Now you have the speed in km/m, so all you need to do is go back to the formula distance = speed * time. When you plug in the values, the time units will cancel and you will be left with the distance the bus covered:

1.2 kilometers / minute * 25 minutes = 30 kilometers