Two towns A and B are connected by a regular bus service with a bus le...
Let vkmh−1 be the constant speed with which the bus travel ply between the towns A and B .
Relative velocity of the bus from A to B with respect to the cyclist = (v − 20)kmh−1
Relative velocity of the bus from B to A with respect to the cyclist = (v + 20)kmh−1
Distance travelled by the bus in time T (minutes) = vT
As per question
Equating (i) and (ii) , we get
= 18v − 18 x 20 = 6v + 20 × 6
or 12v = 20 x 6 + 18 x 20 = 480 or v = 40 kmh−1
Putting this value of v in (i) , we get
40T = 18 x 40 − 18 x 20 = 18 x 20
Two towns A and B are connected by a regular bus service with a bus le...
**Given information:**
- The speed of the man cycling is 20 km/h.
- The bus goes past the man every 18 minutes in the direction of his motion.
- The bus goes past the man every 6 minutes in the opposite direction.
**To find:**
- The period T of the bus service.
**Assumptions:**
- The distance between towns A and B is constant.
- The man is cycling at a constant speed.
**Approach:**
- Let the distance between towns A and B be D km.
- Let the time taken by the bus to travel from A to B be T1 minutes.
- Let the time taken by the bus to travel from B to A be T2 minutes.
**Understanding the problem:**
- When the man is cycling in the direction from A to B, the bus overtakes him every 18 minutes.
- When the man is cycling in the direction from B to A, the bus overtakes him every 6 minutes.
- This means that in the same amount of time, the bus covers a shorter distance in the direction from A to B compared to the direction from B to A.
**Calculating the bus speed:**
- Let the speed of the bus be V km/h.
- In the direction from A to B, the bus covers a distance of D in T1 minutes.
- Therefore, the speed of the bus in the direction from A to B is V = D/T1 km/h.
- In the direction from B to A, the bus covers a distance of D in T2 minutes.
- Therefore, the speed of the bus in the direction from B to A is V = D/T2 km/h.
**Calculating the man's speed:**
- The man's speed is given as 20 km/h.
**Calculating the number of bus trips:**
- In the direction from A to B, the bus overtakes the man every 18 minutes.
- Therefore, the time taken by the bus to complete one trip from A to B is T1 = 18 minutes.
- In the direction from B to A, the bus overtakes the man every 6 minutes.
- Therefore, the time taken by the bus to complete one trip from B to A is T2 = 6 minutes.
**Calculating the period of the bus service:**
- The period T of the bus service is the time taken for the bus to complete one round trip from A to B and back.
- The time taken for the bus to travel from A to B is T1 minutes.
- The time taken for the bus to travel from B to A is T2 minutes.
- Therefore, the period T is T = T1 + T2 = 18 + 6 = 24 minutes.
**Conclusion:**
- The period T of the bus service is 24 minutes.