Q8. Let us air resistance. censider an object launched vertically upward with an
ID: 1781997 • Letter: Q
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Q8. Let us air resistance. censider an object launched vertically upward with an initial speed v. Neglect an (a) [4 pts] The Aiseotential energy of the object at the moment of launch [B] is positive c is zeros the depends on the choice of the "zero level" of potential energy (b) [ the pts) At the moment of launch (as it leaves the launch pad), what can be said about ojectile's kinetic and potential energy? IA] Both kinetic and potential energy are at their maximum values. [B] Both kinetic and potential energy are at their minimum values IC] Kinetic energy is at a maximum; potential energy is at a minimum. ID] Kinetic energy is at a minimum; potential energv is at a maximum. Q9. A bullet of mass m, is fired horizontally with speed v, at a wooden block of mass m resting on a frictionless table. The bullet hits the block and becomes completely embedded within it. After the bullet has come to rest within the block, the block, with the bullet in it, is traveling at speed vw Bekore collision Afier collision mw it (a) (4 ptsj Which of the following quantities, if any, are conserved during this collision? (A] kinetic energy only [B] momentum only [C] kinetic energy and momentum [D] neither momentum nor kinetic energy (b) [4 pts] Which of the following best describes this collision? A] perfectly (completely) elastic [B] perfectly (completely) inelastic C] partially inelasticExplanation / Answer
8 a) the potential energy depends on the choice of the zero level of potential energy. For example, if you choose the launching point to be zero, the potential energy will be zero. If you choose the maximum height to be the zero level, the potential energy will be negative. So the correct answer is Option D
b) At the moment of launch, the velocity(and hence the kinetic energy) is maximum and the potential energy is minimum. So the correct answer is Option C
9 a) Momentum is always conserved in any kind of collision. Hence Option B
b) Since the bullet gets lodged in the object and they move together, maximum kinetic energy is lost. Hence it is a perfectly inelastic collision. Option B.
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