AP Physics C Mechanics Question of the Day

1. $0.64\ \text{J}$
2. $1.28\ \text{J}$ (correct answer)
3. $2.56\ \text{J}$
4. $0.32\ \text{J}$

Explanation: This question tests AP Physics C: Mechanics skills, specifically understanding and calculating translational kinetic energy using the fundamental formula. Kinetic energy (KE) is the energy an object possesses due to its motion, calculated using KE = ½mv², where m is mass and v is velocity. In this scenario, the billiard ball has mass 0.16 kg and moves at 4.0 m/s, requiring direct application of the formula: KE = ½(0.16 kg)(4.0 m/s)² = ½(0.16)(16) = 1.28 J. Choice B is correct because it properly applies the kinetic energy formula with correct squaring of velocity. Choice A (0.64 J) is incorrect as it likely forgets the factor of ½, while choice D (0.32 J) might use velocity without squaring. To help students: Emphasize memorizing the exact formula including the ½ factor and the importance of squaring velocity. Practice substitution problems with various units to build confidence in direct calculations.