Physics, asked by garv7151, 9 months ago

9. a train travels 20 km at a uniform speed of 60 km/h and the next 20 km at a uniform speed of 80 km/h. calculate its average speed

A)68.57 km/h

B)70 km/h

C)65.78 km/h

D)72.36 km/h​

Answers

Answered by ramkumarpeddeti
2

ANSWER :

68.57 Km/h

EXPLANATION :

for 1st

D =20km

S=60km/h

T= D/S

T= 20km/60km/h

t=1/3h

again

t= 20km/80km/h

t= 1/4h

now averagespeed =40/7/12 =68.57 km/s

Answered by sristi200415
0

Answer:

Explanation:

First case:

Distance=20km

=20×1000

=20000m

Speed=60km/hr

=60×1000/3600

=50/3m/s

Total time =distance/speed

=20000×3/50

=1200s

2nd case:

Distance =20km=20000m

Speed =80km/hr

=200/9m/s

Time taken =20000×9/200=900s

Therefore,

Average speed =Total distance/total time

=(400000/2100)m/s

=19.0476190476m/s

=19m/s

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