Question

True and False: 4 Points Fach Any answerS NOT recorded on the Scantron answer page 1. If the vector sum of the external forces on a system is zero, the total momentum of the system is constant. T True F) False 2. In an elastic collision, the total momentum and kinetic energy are conserved. T) TrueF False According to the work-energy theorem for a rotational body, the work done to decrease the angular velocity of a rigid body is positive T) True F) False A constant net torque applied to a rigid body means that the body must have a constant angular acceleration T) True F) False 5. A rotating body can only have a constant angular momentum if its angular velocity is constant T) True F) False 6. For purposes of computing the translational kinetic energy of a rigid body, its mass can be considered as concentrated at the center of mass. To compute the body's moment of inertia, the mass can also be considered as concentrated at the center of mass. T) True F False 7. In five billion years give or take a few hundred million years, our Sun will expand into a red giant star with a radius extending out beyond the planet Mars. If upon expansion the mass is the same, then its angular velocity must increase. T) True F False s. The equation Στ-1α is the rotational equivalent to Newton's Third Law of Motion. T) True F) False

Answer 1

False If the system has constant velocity, then system has some momentum in spite of having net force zero. True In elastic collision no energy loss takes place hence both momentum and kinetic energy is conserves. To decrease angular velocity, work is done on the system, hence negative. therefore False statement. Torque = I alpha (I - Moment of Inertia (always constant for rigid body) alpha - constant for constant torque.) therefore True statement.