rotational motion

  1. P

    What is torque, really? Can it be determined for a point on a circle that is away from its center of the rotation axis by a radius “r”?

    Let's picture a Rolling without slipping Wheel, that constantly accelerates. radius of a wheel/circle is rr. Basically any wheel of a vehicle is rotating around its fixed axis - AoR -(axis of rotation) Most of the times wheels have this AoR perfectly in the center of the...
  2. N

    Energy in rotational motion

    A frictionless pulley has the shape of a uniform solid disk of mass 2.50 kg and radius 20.0 cm. A 1.50-kg stone is attached to a very light wire that is wrapped around the rim of the pulley, and the system is released from rest. (a) How far must the stone fall so that the pulley has 4.50 J of...
  3. J

    Help Deriving Moment of Inertia of Solid Sphere (Where did i go wrong?)

    I am attempting to derive the moment of inertia for a solid sphere by summing an infinate amount of thin spherical shells instead of disks. Sphere has radius R Shells have radius r and thickness dr I=sum(mr^2) = integral(r^2dm). to sub out dm in terms of dr, p=m/v so pdv=dm. dv of a shell...
  4. P

    Help with Past Exam Question on Rolling Disk on Hemisphere

    Hoping to outdo his physics professor, Doofus wants to dramatically demonstrate parabolic motion by throwing a cheese wheel of mass m and radius r off of the top of the UW observatory, which is at a height 3R above the roof of the physics building, as shown in the diagram. Just as he is...
  5. A

    Lever Arm at equilibrium

    Hi, I've attached an image of the problem i am trying to solve, your help would be very much appreciated. I understand the basic principles of moments, such as moment = lever arm x Force. But i am having problems trying to find the solution to the image attached. There needs to be two...
  6. T

    Rotational Kinematics/ Kinetic Energy Problem

    Question: A cylinder of inertia 1.167 kgmm rotates about a vertical frictionless axle with angular velocity 32 radians/second. A second cylinder of inertia 1.6 kgmm is initially not rotating and it drops onto the first cylinder. The two surfaces are rough and they eventually come to the same...
  7. S

    Torque about the wheel's central axis

    A frictional force of 350 N acts on the rim of a 1.7 m diameter wheel to oppose its rotational motion. What is the torque about the wheel's central axis? (Take positive torques to be in the direction of rotation.) Ok ive tried taking 350N*.85 m but i use and it keeps saying i...
  8. P

    Angular acceleration

    A circular saw blade completes 1250 revolutions in 39 s while coasting to a stop after being turned off. Assume constant deceleration. (a) What is the angular deceleration? (b) What is the initial angular speed? Thanks for your help