# 9th physics homework sum-A train travels first 15 km at a uniform speed 30 km/h.next 75 km at uniform speed 50 km/h.last 10 km at a uniform speed of 20 km/h.calculate the average speed.

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Distance D1 = 15 km Speed V1 = 30 kmph Duration T1 = 15/30 = 0.50 hrs

Distance D2 = 75 km speed V2 = 50kmph duration T2 = 75/50 = 1.5 hrs

Distance D3 = 10 km speed V3 = 20 kmph duration T3 = 10/20 = 0.5 hrs

* total D = 100 km total = 2 hours*

average speed = V = total distance / total time duration

*= 100 km / 2 hrs = 50 kmph*

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We can also do this by using the formula:

If you can use the formula, that is fine. Other wise do that in the first method.

Distance D2 = 75 km speed V2 = 50kmph duration T2 = 75/50 = 1.5 hrs

Distance D3 = 10 km speed V3 = 20 kmph duration T3 = 10/20 = 0.5 hrs

average speed = V = total distance / total time duration

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We can also do this by using the formula:

If you can use the formula, that is fine. Other wise do that in the first method.