Question

A train travels with a speed of 60km/h from station A to B and then comes back with a speed of 80Km/h from station B to A. Find:
1) Average speed
2) Average velocity

Answer 1

average speed = total distance/total time = 140km/2h = 70km/h
av. velocity = displacement/total time = 0km/2h = 0

Answer 2

(1.)Average speed
Given That,
Speed in first round (V1)= 60km/h
speed in second round (V2)= 80km/h
Distance = same in both

We can use the formula in which distance is same in both cases, i.e.
$\frac{2V1V2}{V1+V2}$
We will get, $\frac{2*60*80}{60+80}$,
so the answer will be ≈ 68.6 km/h
(2.) Average velocity
Avg velocity =$\frac{Total displacement}{Time Taken}$
=$\frac{0}{x}$
Thus, average velocity is zero.


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