Praxis II General Science

Category - Physics

Alex is running a race, and he is 100 meters from the finish line. However, his opponent is 10 meters in front of him! If Alex and his opponent are both running at 8 m/s, how much faster must Alex run to beat his opponent?
  1. 0.15 m/s
  2. 0.25 m/s
  3. 0.67 m/s
  4. 0.90 m/s
  5. 1.51 m/s
Explanation
Answer: D - Alex needs to run 0.90 m/s faster, or at a total rate of 8.9 m/s, to catch and beat his opponent. At the rate his opponent is running, he will reach the finish line in 90m/8(m/s), or 11.25 seconds. Thus, Alex needs to run 100 meters in less than 11.25 seconds. 100/11.25 = 8.88 m/s, meaning Alex needs to run more than 0.88 m/s, or about 0.90 m/s faster, to beat his opponent.
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