Question

a body travels from A to b and takes some total time, it travels for the half time with the speed 50Km/h and for next half time with the speed 80 km/h. Calculate the average speed.

Answer 1

Hi there,

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Average speed < v_{avg} > = total distance ÷ total time taken.

lets say total time taken = t

and half the time will be t/2 for which the body travels with 50kmph

and for another t/2 it travels with 80kmph...

so..... as we know [speed = distance/ time]

< v_{avg} > = $\frac{50kmph(t/2) + 80kmph(t/2)}{t h}$

⇒ < v_{avg} > = $\frac{(50 + 80) km}{2h}$

⇒ < v_{avg} > = 65 kmph

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Answer 2

Answer:

Average Velocity = 61.53 km/h.

Explanation:

Let the total distance travelled be 2x.

First half distance:

v1 = 50 km/h

t1 = x/v1 = x/50

.°. t1 = x/50

Second half distance:

v2 = 80 km/h

t2 = x/v2 = x/80

.°. t2 = x/80

Total time taken = x/50 + x/80

So, average speed = 2x / x/50 + x/80

=> Average Velocity = 2x / 80x + 50x/4000 = 8000/130 = 61.53 km/h.

.°. Average Velocity = 61.53 km/h