1. N

    Bricks and rotation

    Hey, there is a problem I don't really know how to approach :) it goes: Consider a system of four uniform bricks, like in the sketch Each brick has length = L height = H depth = D What is the maximum distance x that the middle two bricks can be displaced...
  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. A

    AddForce issue after rotation of the object axis

    Hi, I'm new to unity, and I am trying to create a simple game where a cube moves and jump around a field. I encountered a problem, sometimes, when the cube jumps and moves he flips and he falls facing the ground with another face than the starting one, this creates a problem when I use the...
  4. G

    What causes rotation in the Navier-Stokes Equation?

    It is known that rotation in the flow results from the viscous terms in the Navier-Stokes (N-S) equation. However, when deriving the N-S equation from the general principle of linear momentum in Continuum Mechanics, we use the constitutive relation for isotropic Newtonian fluids which states...
  5. J

    Rotation of rigid bodies problem

    Hello everyone, I came across a problem recently which, in hindsight I believe I do not fully understand, and as a consequence of this I cannot seem to get the correct solution no matter how I tackle it. As I have gone through several different attempted solutions to the problem I will just...
  6. E

    Sun's rotation angular velocity.

    Hi: I made a formula to find the angular velocity with which the shade rotates about one's position during one day, assuming the Sun rotates with constant angular velocity $\omega$ in a plane at an angle $\alpha$ with respect to the plane of the horizon. I got $\Omega = (1+tan^2 \omega t)...
  7. S

    Rotation and deformation in fluid mechanics

    We can decompose the dUi/dXj to rotation (Rij) and deformation (Sij) matrices. The question is for a solid-body rotation in which U(theta)=Omega*r/2 and U(r)=0 how come Sij=0 but Rij=Rotation! I do not understand how mathematically it is possible. Rij=d(Ui)/d(Xj)-d(Uj)/d(Xi)...
  8. L

    rotation in a cylindrical cylinder

    what's the difference between zs and hc ? in the pictuire , they are both drawn from the bottom of water to the free surface ...
  9. L

    rotation about fixed axis

    in this notes , the author gave that the IG is the moment of inertia calculated about an axis which is perpendicular to the page ..... moment of inertia calculated about an axis which is perpendicular to the page here means id due to Ft(tangential force) only ? not include Fn ( normal force )...
  10. M

    Kinetic energy of rotation

    What fraction total kinetic energy is rotational for a uniform solid cylinder rolling without slipping on a horizontal surface?
  11. I


    a thin circular ring of mass M and radius r is rotating about its axis with a constant angular velocity(omega).2 objects each of mass m are attached gently to the opposite ends of a diameter of the ring.the ring now rotates with an angular velocity of? how do i start i need a hint....
  12. I


    a ball rolls without slipping.The radius of gyration of the ball about an axis passing through the centre of mass is K.If radius of the ball be R,then the fraction of total energy assosciated with its rotational energy will be?
  13. I


    an angular impulse of 20 nms is appliedto a hollow cylinder of mass 2kg and radius 20 cm.the change in its angular speed is???
  14. N

    Gyro allignment

    Hey guys! WHAT a great forum you have here I have some math difficulty that I was wondering if someone could help me with? I have reading from a gyroscope (measuring acceleration in g) And it is clear it has been misalligned. I have the readings in front of me and I am doing this after the...
  15. S

    Rotation of rigid bodies

    Hi, I can't figure out literally why the average of the instantaneous angular velocities of a rigid body should be different from the average angular velocities in a given time interval. Looking at a question I solved; the average of the instantaneous angular was 0.850 rad/s whilst the average...
  16. K

    Force needed to overcome equilibrium

    I am a little stuck on part b) of the following problem: A 5 m long road gate has a mass of m = 15 kg. The mass is evenly distributed in the gate. The gate is supported at point A by a rod attached to the ground below the gate. Point A is located 20 cm from the left end. The gate rotates...
  17. D

    Suspended ballon and planet rotation

    Got to thinking a little. Suppose you could suspend, say, a balloon at a "normal" balloon flying height (i.e. not at satellite orbit height) and not have it be tossed about by weather and winds - would it just remain over the same spot or would it see the planet drift by under it? I'd be...
  18. P

    Rotation of plane mirror Experiment

    In the experiment Rotation of Plane Mirror: Reflection Lab Part A - YouTube What are some physical applications of the results: i.e. P = 1/2 Q P - Angle of Rotation of Mirror Q - Angle of Rotation of Reflected Ray I think one example is so an automobile can see around a tight corner
  19. S

    Rigid body rotation question (Is my book's answers wrong?)

    The question (with answers) is here and attached: My work is here and attached: If you divide multiply the answers I get by 10, they're equal to the book's answers. Is the book wrong or am I forgetting to take something into...
  20. R

    Rotation about Fixed Axis

    Hi, Here's my question: A uniform rod AB of mass m is released from rest when it is at 60degrees from the surface of the earth. Assuming the friction force between end A (that's the end that touches the surface) and the surface is large enough to prevent sliding, determine (for the instant just...