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50. Two bodies stick together after collision. Is the colli-sion elastic or inelastic? |
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Answer» In collisions between two isolated objects Newton's third law implies that momentum is always conserved. In collisions, it is assumed that the colliding objects interact for such a short time, that the impulse due to external forces is negligible. Thus the total momentum of the system just before the collision is the same as the total momentum just after the collision. Collisions in which the kinetic energy is also conserved, i.e. in which the kinetic energy just after the collision equals the kinetic energy just before the collision, are calledelastic collision. In these collisions no ordered energy is converted into thermal energy. Collisions in which the kinetic energy is not conserved, i.e. in which some ordered energy is converted into internal energy, are calledinelastic collisions. If the two objects stick together after the collision and move with a common velocityvf, then the collision is said to beperfectly inelastic. |
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