Q132
ArithmeticSpeed, Time & Distance
Two cars start towards each other, from two places A and B which are at a distance of 160 km. They start at the same time 8:10 am. If the speeds of the cars are 50 km per hour and 30 km per hour respectively, they will meet each other at
- a.10:10 am
- b.10:30 am
- c.11:10 am
- d.11:20 am
Answer: (A) 10:10 am
The cars move towards each other, so their relative speed is $50 + 30 = 80$ km/h. Time to meet $= \frac{160}{80} = 2$ hours, and 2 hours after 8:10 am is 10:10 am. They meet $50 \times 2 = 100$ km from A and $30 \times 2 = 60$ km from B. Rule: for bodies moving in opposite directions add the speeds; for the same direction subtract them. If the two cars were travelling in the same direction, the faster one would close a 160 km gap in $\frac{160}{20} = 8$ hours.