# physics

On a 120 km track, a train travels the first 30 km at a uniform speed of 30km/h. How fast must the train travel the next 90 km so as to average 60km\h for the entire trip?

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1. Let the train must travel with a speed of x km .

Average speed = Total distance travelled\Total time taken

60km\hr =30 km + 90km\x + 1hr

x +1hr =120km \60

x = 2 - 1

= 1
time taken to cover 90km = 90\1
=90km\hr
ans - The train must travel the next 90 km with a speed of 90 km/h so that the average speed is 60 km/h.

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posted by Miranda
2. average speed = total distance
travelled\total time
60km\hr = 30km +90km\x km.
x +1hr =120km \60
x =2-1
=2
answere -the train must travel the next 90 km with a speed of 90 km/h so that the averange speed is 60 km/h.

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3. Average speed = total distance / total time taken
therefore, 60 km/hr = 30 km + 90 km /x + km
x = 120km / 60km
x = 2 - 1
x = 1

ANSWER : The train must travel the next 90 km with a speed of 90 km/hr so that the average speed is 60 km/hr.

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4. on a 120 km long railway track a train first 80 km at a uniform speed of 160km/hr. calculate the speed in which the train should travel rest of the track so as to get a speed of 80 km/hr.

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5. 90 km/ hr

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posted by Harshi
6. Speed of train in first 30 km
V1=30km/h
Speed of the train in the next 90 km , v2

Average speed = 60 km/ h=( V1+v2)/ 2

V2=90 km / hr

7. 90km/hr

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posted by Shaurya
8. 90 km/h

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posted by ammu
9. 90km/hr

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10. A train travels the first 30 kilometre of 120 kilometre track with a uniform speed of 30 kilometre per hour what should be the speed to cover the remaining distance of the track so that its average speed is 60 kilometre for the entire trip

Pls give me answer

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11. 90km/he

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posted by Mira

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