Question

Two cars A and B race each other. The Car A ran for 2 min at a speed of 7.5 km/h, slept for 56 min and again ran for 2 min at a speed of 7.5 km/h. find the average speed of the car A in the race.

Answer 1

total distance covered=2*60*7.5*1000/3600+2*60*7.5*1000/3600. =500m. total time taken =60min=3600s. thus speed =500/3600 =5/36m per s

Answer 2

Question :

Two cars A and B race each other. The Car A ran for 2 min at a speed of 7.5 km/h, slept for 56 min and again ran for 2 min at a speed of 7.5 km/h. find the average speed of the car A in the race.

Answer :

The Car A run at the speed of 7.5 km/hr for time 2 min or 1/30

Distance = speed ✖ time

$7.5 \times \frac{1}{30}$

0.25 km

Car A take rest for 56 min

Then car run again at the speed of 7.5 km/hr for time 2 min or, 1/30

Distance = speed ✖ time

$7.5 \times \frac{1}{30}$

0.25 km

Total distance = (0.25 + 0.25)

0.50 km

Total time taken = (56 + 2 + 2)

60 min = 1 hour

$average \: speed \: = \frac{total \: distance}{total \: time} \\ \frac{0.50}{1}$

0.5 km / hr