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April 18, 2015

April 18, 2015

Posted by **Shelby** on Wednesday, October 14, 2009 at 6:28pm.

2) To qualify for the finals in a racing event, a race car must achieve an average speed of 250 km/h on a track with a total length of 1600m. if a particular car covers the first half of the track at an average speed of 230 km/h, what minimum average speed must it have in the second half of the event to qualify?

- physic -
**MathMate**, Wednesday, October 14, 2009 at 7:13pm1. Velocity = Displacement / time

Displacement = Final position - initial position

Note that displacement does not have to equal distance if the bus travels in a zig-zag route.

2. Speed = distance / time

Total distance = 1600 m.

230 km/h = 230000 m/3600 s = 63.889 m/s

250 km/h = 250000 m/3600 s = 69.444 m/s

Time spent on first half of track

=800/63.889 s.

Total time permitted = 1600/69.444 s

Time left, t = 1600/69.444 - 800/63.889 s

So speed required = 800 m / t

Convert to km/h.

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