Dear Reader, Below are three distance speed problems for you to practice.
A Maruti Swift car started from Chennai towards Mumbai at 7 am. A Tata Indigo car newly purchased started from Chennai at 10 am towards Mumbai and the second vehicle was able to cross the first vehicle at 6 pm on the same day. If Tata Indigo was running at an average speed of 80 km per hour what would have been the speed of Maruti Swift car?
a) 64.24 km/hour b) 59.12 km/hour c) 58.18 km/hour d) 65.42 km/hour
Answer : c) 58.18 km/hour
Tata Indigo car had taken 8 hours to cross Maruti Swift running at 80 km/hour.
Distance covered by Tata Indigo in 8 hours = 80 x 8 = 640 km
This distance has been covered by Maruti Swift in 11 hours (as it started at 7 am and was crossed by Tata Indigo at 6 pm)
So average speed of Maruti Swift - 640 /11 = 58.18 km/hour
An Ashok Leyland Truck started from Ennore factory towards Kolkata at 6 am and it was running at an average speed of 60 km per hour. Another Tata Truck started from Ennore at 8.30 am and crossed the Ashok Leyland at 4.30 pm. What is the average speed of Tata Truck?
a) 78.75 km/hour b) 74.75 km/hour c) 72.50 km/hour d) 76.85 km/hour
Answer : a) 78.75 km/hour
Ashok Leyland has run 10 ½ hours before the trucks met at an average speed of 60 km/hour
Distance covered by Ashok Leyland - 60 x 10 ½ = 630 km
This distance has been covered by Tata Truck in 8 hours (as it started at 8.30 am and crossed the other truck at 4.30 pm)
Average speed of Tata Truck = 630 / 8 = 78.75 km/hour
A Tata Indica car started from Hyderabad towards Madurai at 5.30 am and travelled at an average speed of 50 km/hour. An Innova car started at 8.30 am from Hyderabad again towards same destination at an average speed of 66 2/3 km/hour. At what time Innova will cross the Tata Indica Car?
a) 4.30 pm b) 5.30 pm c) 3.30 pm d) 6.40 pm
Answer : b) 5.30 pm
Tata Indica starts at 5.30 which is 3 hours before Innova started. Therefore it has run for 3 hours at 50 Km/hr speed. Hence Tata Indica car has run 50 x 3 = 150 km by the time Innova starts.
The relative speed of Innova car = Innova Speed - Indica Speed = 66 2/3 - 50 = 16 2/3 km/hour
(Note: To calculate relative speed we are subtracting Indica's speed from Innova's speed as they travel in same direction. If they were travelling in opposite directions we would had added the speeds.)
Innova will take Distance/Relative Speed = (150) / (16 2/3) = 9 hours.
So Innova will cross Tata Indica 9 hours after 8.30 am i.e at 5.30 pm