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A race car completes a lap on a 1600 m long track with an average speed of 250 km/h. If the car's average speed on the first half of the track was 215 km/h, what was its average speed (in km/h) on the second half?

Respuesta :

Its average speed (in km/h) on the second half is 298.76 km/hr

Explanation:

Length of track = 1600 m

Average speed = 250 km/h = 69.44 m/s

We have

      Distance = Speed x Time

      1600 = 69.44 x time

      Time = 23.04 seconds

Total time = 23.04 seconds

Half of the track = 0.5 x 1600 = 800 m

Speed on first half = 215 km/hr = 59.72 m/s

We have

      Distance = Speed x Time

      800 = 59.72 x time

      Time = 13.40 seconds

Time taken to complete remaining half = 23.04 - 13.40 = 9.64 seconds

Distance = 800 m

We have

      Distance = Speed x Time

      800 = Speed x 9.64

      Speed = 82.99 m/s = 298.76 km/hr

Its average speed (in km/h) on the second half is 298.76 km/hr

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