Question

3
3- A train tranels 20 km at a
uniform speed of 60 km h and
the next 20 km at a uniform
speed of 80 km hi calculate
its average
speed.​

Answer 1

Answer:

time taken to travel 20 km at 60km/hr=20/60=0.33hr

time taken to travel nxt 20 km at 80km/hr=20/80=0.25hr

avg speed=total distance travelled / total time taken=40/0.58=68.96km/hr

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Answer 2

Answer :

Given -

• Train travels 20 km per hour the speed of 60 km/hr
• Then, it travels 20 km at the speed of 80 km/hr

To Find -

• Average speed ?

Solution -

We know, Speed = Distance/Time.

Hence, Time = Distance/Speed.

Case 1 :

• Distance = 20 km
• Speed = 60 km/hr

So, Time = 20/60 = 0.33 hr

Case 2 :

• Distance = 20 km
• Speed = 80 km/hr

So, Time = 20/80 = 0.25 hr

Now, Average Speed = Total Distance/Total Time

So, Average Speed = (20 + 20)/(0.33 + 0.25)

⇒ 40/0.58

⇒ 68.96 km/hr

⇒ Or 68.96 * 5/18

⇒ 19.15 m/s

Hence, Average speed = 68.96 km/hr OR 19.15 m/s.