1) The kinetic energy of a particle of mass m can be expressed as K 12m, where p
ID: 2305750 • Letter: 1
Question
1) The kinetic energy of a particle of mass m can be expressed as K 12m, where p is the particle"s momentum. Given this relationship, how it is possible that an inelastic collision can conserve momentum, but not conserve kinetic energy? A) Inelastic collisions are only theoretical constructs; in a real collision kinetic energy is always conserved. B) It is possible to conserve momentum without conserving kinetic energy because the mass of an object can change during a collision. C) Conservation laws apply to an entire system, not individual particles. D) Particles involved in an inelastic collision simply "exchange" their velocities, so momentum must be conserved, while kinetic energy need not be conserved E) Kinetic energy is conserved in an inelastic collision. 2) Which of the following is true regarding an object undergoing simple harmonic motion? A) The net force exerted on the object is constant. B) The period of oscillation is independent of the amplitude. C The angular frequency is proportional to the square root of the amplitude. D) The object's acceleration always points towards equilibrium. E) The object must be part of a spring-mass system. 3) Which of the following is a statement of the work-energy theorem? A) T he net work done by an object is equal to the change in its kinetic energy B) The energy of a system is only conserved if no work is done. C) The net work done on an object is equal to the change in its kinetic energy. D) The work done on an object by non-conservative forces is equal to the change in its kinetic energy.Explanation / Answer
1] In any collision, be it elastic or inelastic, the kinetic energy and momentum of a SYSTEM of two interacting bodies is evaluated before and after their collision.
Now K = p2/2m and we know that momentum p is conserved in an inelastic collision. But one cannot reach a conclusion that if momentum is conserved then from above equation, the kinetic energy will be conserved too since the momentum of the collective system is conserved whereas the above equation only speaks about one particle.
therefore, the answer is [C].
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