Correct Answer - Option 1 : 10
Concept:
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Speed: Total distance traveled by the total time taken is called speed.
- Speed measures how fast the body is moving.
\(\rm speed = \dfrac{distance}{time}\)
- Average speed: It is defined as the total distance traveled by the total time taken.
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Odometer: It is the device that is used to measure the distance traveled by a vehicle.
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Average speed: The total distance traveled by the total time taken will give the average speed.
\(\rm Average \ speed = \dfrac{total \ distance}{total \ time}\)
- Conversion of speed from km / hr to m /s
1 km = 1000 m
1 hr = 3600 second
So,1 km / 1 hr = 1000 m / 3600 second = \(\frac{5}{18} \ m / s\)
Calculation:
The initial reading of the odometer = 6640 km (at 8.00)
Final reading of the odometer = 6712 km (at 10.00)
Distance travelled d = 6712 km - 6640 km = 72 km
Time taken = 10;00 - 8:00 = 2 hr
So, average speed = (total distance) / (total time) = 72 km / 2 hr = 36 km / hr
Now, this has to be converted into m /s by multiplying it with \(\frac{5}{18} \ m / s\)
So,
\(36 \ km /hr = 36 \times \frac{5}{18} m /s = 10\ m /s\)
So, the correct option is 10 m / s.
Students may write answer in km/hr instead of m /s . Questions should be always read properly.
