Physics · Forces and Motion
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A person, travelling on a motorway a total distance of 200 km,travels the first 90 km at an average speed of 80 km/hr. Which average speed must be obtained for the rest of the journey if the person is to reach the destination in a total time of 2 hours 0 minutes?
- A
110 km/hr
- B
120 km/hr
- C
122 km/hr
- D
126 km/hr
Average speed = total distance / total time
Time taken to travel first 90 km
= 90/80=1.125 h
= 1h 7.5 min
For the rest of the journey,
Distance that needs to be travelled
=200-90 = 110 km
Time remaining
=2h-1.125 h- 0.875 h
Average speed = total distance/ total time
= 110 / 0.875 = 126 km/h
As it is numerical, it can have only one answer.
This option is incorrect.
Average speed = total distance / total time
Time taken to travel first 90 km = 90/80=1.125 h = 1h 7.5 min
For the rest of the journey, Distance that needs to be travelled
=200-90 = 110 km
Time remaining =2h-1.125 h- 0.875 h
Average speed = total distance/ total time = 110 / 0.875 126 km h1
This option is incorrect.
Average speed = total distance / total time
Time taken to travel first 90 km = 90/80=1.125 h = 1h 7.5 min
For the rest of the journey, Distance that needs to be travelled
=200-90 = 110 km
Time remaining =2h-1.125 h- 0.875 h
Average speed = total distance/ total time = 110 / 0.875 126 km h1
This option is incorrect.
Average speed = total distance / total time
Time taken to travel first 90 km = 90/80=1.125 h = 1h 7.5 min
For the rest of the journey, Distance that needs to be travelled
=200-90 = 110 km
Time remaining =2h-1.125 h- 0.875 h
Average speed = total distance/ total time = 110 / 0.875 126 km h1
Average speed = total distance / total time
Time taken to travel first 90 km = 90/80=1.125 h = 1h 7.5 min
For the rest of the journey, Distance that needs to be travelled
=200-90 = 110 km
Time remaining =2h-1.125 h- 0.875 h
Average speed = total distance/ total time = 110 / 0.875 126 km h1
As it is numerical, it can have only one answer.
Tagged under Physics · Forces and Motion · 2017