a train travels a 20 km. at a uniform speed of 60 km/hr. and next 20 km. at a uniform speed of 80km/hr. Calculate the average speed of
time for slow part = 20 km/(60 km/h) = 1/3 hrs
time for faster part = 20 km/(80 km/h) = 1/4 hrs
total time = 1/3 + 1/4 hrs or 7/12 hrs
total distance = 40 km
avg speed
= total distance/total time
= 40 km/(7/12 hrs)
= appr 68.6 km/h
To calculate average speed, you need to find the total distance traveled and the total time taken.
In this case, the train travels a total of 20 km at a speed of 60 km/hr and then another 20 km at a speed of 80 km/hr.
Let's calculate the time taken for each leg of the journey:
Time taken for the first 20 km at a speed of 60 km/hr:
Time = Distance / Speed
Time = 20 km / 60 km/hr = 1/3 hr
Time taken for the next 20 km at a speed of 80 km/hr:
Time = Distance / Speed
Time = 20 km / 80 km/hr = 1/4 hr
Now, we can find the total time:
Total time = Time for the first leg + Time for the second leg
Total time = 1/3 hr + 1/4 hr
Total time = 7/12 hr
Next, we can calculate the total distance covered:
Total distance = Distance for the first leg + Distance for the second leg
Total distance = 20 km + 20 km = 40 km
Finally, we can calculate the average speed:
Average speed = Total distance / Total time
Average speed = 40 km / (7/12) hr
To divide fractions, we multiply the first fraction by the reciprocal of the second fraction:
Average speed = 40 km * (12/7) hr
Average speed ≈ 68.57 km/hr
Therefore, the average speed of the train for the entire journey is approximately 68.57 km/hr.