PHYS 211Exam #3 Study Guide Lectures: 19-29Lecture 19 (October 9th)I. MomentumMomentum: p=mv Units: kgm/sWhat is the momentum of a 70 kg runner in the 100 m sprint? T=10sT=10s v = 100m/10s = 10m/sp = 700 kgm/sA 1.5 kg football is kicked at 20m/s at an angle of 30 degrees above the horizontal. What is p?p = mv = 30 kgm/s at 30 degreesvx = vcos = 17m/sƟvy = vsin = 10 m/sƟpx = 26 kgm/s py = 15kgm/sWhat is the change in momentum of a .17kg cue ball hitting a cushion at 5m/s and 45 degrees?vx = vicos = 5m/s pƟx = .84kgm/svy = visin = -5m/s pƟy = -.84kgm/svfy = vfcos = 3.5m/s pƟy = .60kgm/svfx = vfsin = 3.5m/s pƟx = .60kgm/sLecture 20 (October 10th)I. Impulse Impulse is the change in momemtumI = Δp = FΔtII. Conservation of Linear MomentumWhen collisions happen quickly enough that the effects of external forces can be ignored during a collision, momentum is conserved.Lecture 21 (October 13th)I. Inelastic CollisionsWith inelastic collisions, some of the initial kinetic energy is lost to thermal or potential energy. It may also be gained during explosions, as there is the addition of chemical or nuclear energy.A completely inelastic collision is one where the objects stick together afterwards, so there is only one final velocity. Most collisions are inelastic, but not completely inelastic.II. Elastic CollisionsIn an elastic collision, both energy and momentum are conservedLecture 22 (October 15th)I. Center of MassFnet = MacmXcm = ΣmixiMSuppose a pregnant 65kg woman gains 8 kg of mass 18cm in front of her hips. Where is her new center of mass?Xcm = ΣmixiM = (65kg) + (18cm)(8kg)73kg = .02mLecture 23 (October 16th)I. Angular MeasureII. Angular Speed and VelocityLecture 24 (October 17th)I. Uniform Circular Motion II. Centripetal Acceleration Lecture 25 (October 20th)I. Centripetal Acceleration PracticeHow fast must a ferris wheel turn for a person to feel weightless? R=5mΣF = Fnetmg-N = macg=acg = v2/rv = 7m/sII. Angular AccelerationIII. Tangential AccelerationLecture 26 (October 22nd)I. Newton’s Law of GravitationLecture 27 (October 23rd)I. Centripetal Acceleration PracticeHow fast would a space station r=500m need to spin to mimic gravity?ΣF = FnetN = maN = mgmg = macg = v2/rV=70m/sII. TorqueLecture 28 (October 24th)I. Torque and EquilibriumLecture 29 (October 27th)I. Rotational DynamicsII. Rotational Work and Kinetic