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A car travels 54 km/h for …

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A car travels 54 km/h for first 20 seconds ;36 km/h for next 30 seconds and finally 18 km/h in 10 seconds .find its average speed

Posted by Karan Kingra 5 years, 11 months ago

Sia ? 5 years, 11 months ago

Conversion:
54 km/hr = 54 $\times \frac{5}{18}$ = 15 m/s
36 km/hr = 36 $\times \frac{5}{18}$ = 10 m/s
18 km/hr = 18 $\times \frac{5}{18}$ = 5 m/s

Now, First,
Speed = 15 m/s and Time = 20 s
Distance = Speed x Time = 15 x 20 = 300 m

Second,
Speed = 10 m/s and Time = 30 s
Distance = 10 x 30 = 300 m

Third,
Speed = 5 m/s and Time = 10 s
Distance = 5 x 10 = 50 m

Now Total Distance = 300 + 300 + 50 = 650 m
Total time = 20 + 30 + 10 = 60 s
Therefore, Average Speed = $\frac{650}{60} = \frac{65}{6}$ m/s

ANSWER

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