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Praxis II General Science

Category - Physics

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Sam is hit by a baseball moving at 10 m/s, but claims it didn’t hurt at all! His “friend” Alex then hits another ball at him, this time at 20 m/s, and it really hurt Sam! What accounts for this difference in impact felt?
  1. Double the speed results in 4 times the kinetic energy.
  2. Double the speed results in more force applied in a smaller area.
  3. The ball was moving faster, and thus compressed air in front of it into a small sonic blast.
  4. The second ball was a curveball.
  5. Sam is lying, and the second ball didn’t hurt either.
Explanation
Answer: A - A ball moving at twice the speed has 4 times the kinetic energy. Kinetic energy is calculated by E = ½*mv2, so velocity is the greatest factor. Thus, although the ball was moving twice as fast, it held 4 times the energy as the first ball, resulting in a much bigger impact.
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