For “continuous” objects, use table below (p. 263 of book).Physics 101: Lecture 13, Pg 11 Merry Go Round KE = 4 x ½ m v2 = 4 x ½ m w r2 = ½ I w2 Where I = 4 m r2 Further mass is from axis of rotation, greater KE it has. B A Four kids (mass m) are riding on a (light) merry-go-round rotating with angular velocity w=3 rad/s. In case A the kids are near the center (r=1.5 m), in case B they are near the edge (r=3 m). A) KA > KB B) KA = KB C) KA < KBPhysics 101: Lecture 13, Pg 12 Inertia Rods Two batons have equal mass and length.Ĭompare the kinetic energy of the kids on the two rides. Which will be “easier” to spin A) Mass on ends B) Same C) Mass in center I = S m r2 Further mass is from axis of rotation, greater moment of inertia (harder to spin)Physics 101: Lecture 13, Pg 13 Preflight: Rolling Race (Hoop vs Cylinder) A solid and hollow cylinder of equal mass roll down a ramp with height h. Which has greatest KE at bottom? A) Solid B) Hollow C) Same 25% 20% 54% “Both start with same PE so they both end with same KE.”Physics 101: Lecture 13, Pg 14 Preflight: Rolling Race (Hoop vs Cylinder) A solid and hollow cylinder of equal mass roll down a ramp with height h. Which has greatest speed at the bottom of the ramp? A) Solid B) Hollow C) Same 50% 17% 33% “Well, I don't see how rolling things down a ramp would make me a dare-devil, thrill seeker.” “Evel Knievel must be ‘rolling’ in his grave at such a travesty” I = MR2 I = ½ MR2Physics 101: Lecture 13, Pg 15 Main Ideas Rotating objects have kinetic energy KE = ½ I w2 Moment of Inertia I = S mr2 Depends on Mass Depends on axis of rotation Energy is conserved but need to include rotational energy too: Krot = ½ I w2Physics 101: Lecture 13, Pg 16 Massless Pulley Example Consider the two masses connected by a pulley as shown.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |