Translational Motion - General Physics - Solved Past Paper, Exams of Physics

Download Translational Motion - General Physics - Solved Past Paper and more Exams Physics in PDF only on Docsity! 1. (25 pts) a) (5 pts) An object’s resistance to changes in translational motion is quantified by what we call mass. What is it that quantifies an object’s resistance to changes in rotational motion? Moment of inertia is what quantifies an object’s resistance to changes in rotational motion. Just inertia is not correct. An object’s inertia is it’s resistance to change in translational motion. You must specify that it is the moment of inertia. b) (5 pts) On what physical aspect(s) of the object does this resistance to changes in rotational motion depend? Moment of inertia depends on both the mass and shape of the object, with respect to the axis of rotation. Note that stating the radius is not really correct. A wheel can have different moments of inertia, depending on the axis of rotation, even though its radius is the same. c) (5 pts) What condition(s) must be met to ensure that an object is in equilibrium? The net force must be zero and the net torque must be zero. If you state this in equation form, note that both force and torque are vectors and as such should be written with vector symbols, ∑ ~F = 0 , ∑ ~τ = 0 d) (5 pts) Is it possible for an object to be rotating yet also to be in equilibrium? Why or why not? Certainly. As long as there is no net torque, the angular acceleration is zero and it is in equilibrium. If the angular acceleration is zero, that implies that the angular velocity is constant, but not any particular constant value. So it could be zero, but it could also be non-zero. e) (5 pts) A block slides down a hill without friction. A solid cylinder rolls down a hill of the same shape and height. Which will be traveling faster at the bottom of the hill? Explain. The block that slides with no friction will be traveling faster at the bottom since all of the gravitational potential energy goes into translational kinetic energy. The initial potential energy of the rolling object will go into both translational and rotational kinetic energies. Thus the translational kinetic energy will be less than if it had been only sliding and not rolling. Note that the cylinder doesn’t really lose energy to rotation. It still has all the energy it started with, it just didn’t go into translational kinetic energy. Also note that while there must be friction acting on the cylinder to make it rotate, this friction does not do any work since the point of contact between the cylinder and the ground does not move.