Question

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

Answer 1

0.5 km /hr

Explanation:

distance = speed-time

d1 = 7.5×2/60 d1 = 0.25 km

d2 = 7.5x2/60

d2 = 0.25 km

Total distance = d1+d2 = 0.5 km Total time = 2+2+56= 60min = 1 hr

Average speed = 0.5/1 = 0.5 km/hr

Answer 2

Answer:

Two cars A and B race each other. Car A ran for 2 minutes at a speed of 7.5 km/h, and again ran for 2 minutes at a speed of 7.5 km/h, the average speed of car A in the race is $7.3km/h$

Explanation:

• The average speed is the total distance divided by time to travel the total distance

       $Average speed=total distance/total time$

From the question, we have

speed of the car during the first period $v_{1}=7.5km/h$

time taken for it $t_{1} =2mnt=2/60=0.03h$

⇒ distance traveled here is $distance=speed*time$

⇒$d_{1} =7.5*0.03=0.22km$

speed of the car in the next hours $v_{2} =7.5km/h$

time taken $t_{2} =2mnt=2/60=0.03hr$

distance traveled $d_{2} =7.5*0.03=0.22km$

⇒ the average speed of car A = $\frac{d_{1} +d_{2} }{t_{1} +t_{2} }$

⇒ $\frac{d_{1} +d_{2} }{t_{1} +t_{2} }=\frac{0.22+0.22}{0.03+0.03}$

⇒           =$7.3km/h$