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

The average speed of car A is 0.5 km/hr

GIVEN

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.

TO FIND

The average speed of car A in the race.

SOLUTION

We can simply solve the above problem as follows;

We know that,

Average speed = Total distance covered/Total time taken

Total time = 2+56+2 = 60 min = 1 hour

Distance covered by car A for 2 min at a speed of 7.5km/h = 7.5 × 2/60 = 0.25 km

Distance covered by car A for the last 2 min = 0.25 km

Since the driver slept for 56 min so no distance travelled in the time period

Therefore, Total distance covered = 0.25+0.25 = 0.5 km

Average speed = 0.5/1 = 0.5 km/hr

Hence, The average speed of car A is 0.5 km/hr

#Spj2

Answer 2

Car A travels with an average speed of 0.5 km/h.

Given,

Cars that are racing=A, B

Speed of car A=7.5 km/h

Time that it ran at the speed of=2 minutes

Time that it resting for=56 minutes

Speed of the car after resting=7.5 km/h

Time that it ran after resting=2 minutes.

To find,

the average speed of the car A in the race.

Solution:

• Average speed is equal to he ratio of the total distance covered to the time taken to cover it.
• Average speed is a scalar quantity.

Average speed=Total distance covered/Total time taken.

$Speed=\frac{Distance}{Time} \\7.5=\frac{Distance}{\frac{2}{60} } \\7.5=\frac{Distance}{\frac{1}{30} }\\Distance=7.5X{\frac{1}{30} }\\Distance\frac{5}{20} \\Distance=0.25 km.$

The distance covered before resting is 0.25 km.

It rests for 56 minutes then.

$Speed=\frac{Distance}{Time} \\7.5=\frac{Distance}{\frac{2}{60} } \\7.5=\frac{Distance}{\frac{1}{30} }\\Distance=7.5X{\frac{1}{30} }\\Distance\frac{5}{20} \\Distance=0.25 km.$

The distance covered after resting is also 0.25 km.

Total distance covered=(0.25+0.25) km

Total distance covered=0.5 km.

Total distance covered is 0.5 km.

Total time taken to cover 0.5 km,

$=(\frac{2}{60} +\frac{56}{60} +\frac{2}{60}) hours\\=(\frac{2+56+2}{60} )hours\\=(\frac{60}{60} ) hours\\=1 hour.$

Time taken to cover 0.5 km is 1 hour.

Average speed of car A,

$=\frac{0.5}{1}\\=0.5 km/h.$

The average speed of car A is 0.5 km/h.

#SPJ2