Time and Distance

Time and Distance

• Speed = Distance/Time
• Distance = Speed × Time
• Time = Distance/Speed

To convert Kilometers per Hour(km/hr) to Meters per Second(m/s)

To convert Meters per Second(m/s) to Kilometers per Hour(km/hr)

1. If some distance is travelled at x km/hr and the same distance is travelled at y km/hr then the average speed during the whole journey is given by:
Average Speed=

2. If a person travels a certain distance at x km/hr and returns at y km/hr, if the time taken to the whole journey is T hours then the one way distance is given by
One Way Distance

3. If two persons A and B start their journey at the same time from two points P and Q towards each other and after crossing each other they take a and b hours in reaching Q and P respectively, then

4. If the ratio of the speeds of A and B is a : b, thenthe ratio of the times taken by them to cover the same distance is

5. If the same distance is covered at two different speeds S1 and S2 and the time taken to cover the distance are T1 and T2, then the distance is given by

Example:

A man crosses a road  250 metre wide in 75 seconds. His Speed in Km/hr is:
a) 10
b) 12
c) 12.5
d) 15
Solution:

Example:

A train 200 metre long running at 36 Kmph takes 55 seconds to cross a bridge. The length of the bridge is:
a) 375 m
b) 300 m
c) 350 m
d) 325 m
Solution:

Example:

A train 100 m long is running at the speed of 30 Km/hr. The time(in seconds) in which it will pass a man standing near the railway line is:
a) 10
b) 11
c) 12
d) 15
Solution:

Example:

Two trains 105 metres and 90 metres long, run at the speed of 45 Km/hr and 72 Km/hr respectively, in opposite directions on parallel tracks. The time which they take to cross each other, is:
a) 8 seconds
b) 6 seconds
c) 7 seconds
d) 5 seconds
Solution:

Example:

Two trains of equal length are running on parallel lines in the same direction at 46 Km/h and 36 Km/h. The faster train passes the slower train in 36 seconds. The length of each train is:
a) 82 m
b) 50 m
c) 80 m
d) 72 m
Solution:

Example:

The student go to school at the rate of 2.5 Km/h and reaches 6 minutes late. If he travels at the speed of 3 Km/h, he is 10 minute early. The distance between the school and his house is:
a) 5
b) 4
c) 3
d) 1
Solution:

Example:

A train passes a platform 110 m long in 40 seconds and a boy standing on the platform in 30 seconds. The length of the train is:
a) 100 m
b) 110 m
c) 220 m
d) 330 m
Solution:

Example:

Walking at 6/7th of his usual speed a man is 25 minutes late. His usual time to cover this distance is:
a) 2 hours 30 minutes
b) 2 hours 15 minutes
c) 2 hours 25 minutes
d) 2 hours 10 minutes
Solution:

Example:

A train moves with a speed of 30 Kmph for 12 minutes and for next 8 minutes at a speed of 45 Kmph. Find the average speed of the train?
a) 37.5 Kmph
b) 36 Kmph
c) 48 Kmph
d) 30 Kmph
Solution:

Example:

The speed of two train are in the ratio 6:7. If the second train runs 364 Km in 4 hours, then speed of the first train is:
a) 60 Km/h
b) 72 Km/h
c) 78 Km/h
d) 84 Km/h
Solution:

Question Type 11: Based on Races

Example:
In a race of 200 metres, B can give a start of of 10 metres to A, and C can give a start of 20 metres to B. The start that C can give to A, in the same race is:
a) 30 m
b) 25 m
c) 29 m
d) 27 m
Solution: