**Time and Distance ****Formula**

- Speed = (Distance / Time)
- Distance = Time × Speed
- Time = Distance / Speed
- When we need to change x km/hr to m/sec, then multiply it by
**5/18**

x km/hr = (5 × x)/18 m/sec

- When we need to change x m/sec to km/hr, then multiply it by
**18/5**

x m/sec = (18 × x)/5 km/hr

- If the ratio of speeds of A and B is a:b, then the ratio of the times taken by them to cover the same distance is
**(1/a) : (1/b) or b:a.** - In fact, there exists an inverse relationship between distance and time.

__Examples__

__Examples__

**Q-1. A man covers a distance of 810 meters in 1 min 30 seconds. Find his speed in km/hr.**

**Solution-**

Time = 1 min 30 seconds = 90 seconds

Distance = 810 meters

Speed = 810/90 = 9 m/s

Now, Speed in km/hr

9 × 18/5 = 32.4 km/hr (Ans.)

**Q-2. A train covers a distance of 810 km in 9 hours. Find the speed in m/sec.**

**Solution-**

Time = 9 hours

Distance = 810 kilometers

Speed = 810/9 = 90 km/hr

Now, Speed in m/sec

90 × 5/18 = 25 m/sec (Answer)