a motorcycle drives from one point to another point at a speed of 10km/h and returns at the speed of 20km/h , what's the average speed of the motorcycle?
Answers
Answer:
I solved it by using a simple derived formula.
i hope it will help u out.
plzz mark me as brainliest.
Explanation:
if u want derivation of this formula i can give u.
Explanation:
Average speed = (Total distance) / (total time)
let the distance between two points A and B be 'x' km.
Time taken to go from A to B = T1
Time taken to return from B to A = T2
Using the relation: Time taken = Distance/speed
we get:
T1 = x/10 hours
T2 = x/20 hours
now,
Total distance = x + x = 2x km
Total time = T1 + T2 = {(x/10) + (x/20)} hours
= (3x/20) hours
Average speed = (Total distance/ total time)
= {(2x) × 20} / (3x) km/h
= (40x / 3x) km/h
= 13.33 km/h
Note: You might think that average should be 15 km/h which is the average of 20 and 10. But we got the answer 13.33 km/h. why it is so? And what is the validity of such answer.
Well I must say that in this case you can check your answer by this analogy.
*He goes with a speed of 10 km/h and returns with a speed of 20 km/h. so, he spends more time in 10 km/h part than 20 km/h. So, your answer must lies closer to 10 km/h which in our case is 13.33 km/h. So it makes sense.
The answer is not 15 km/h because the time taken to go and come back will be different. If he had taken same time then you can directly find the average no problem there.
But in this case go with formulae and you will get the answer pretty easily and check with the analogy if it agrees or not.
hope it helps!!