posted by .

I have two questions, both are about angular momentum so I thought I'd post them together. I'm really confused on anything regarding rolling wheels and things like that (help me please!. It seems as though the whole chapter was amassed of all of the topics I cant wrap my head around. For both of these, the only work I have down is angular momentum l=rXp, or m(rXv), or =rmvsintheta. Any help would be so great and much appreciated. Thanks so much in advance!

1. A particle is acted on by two torques about the origin: τ1 has a magnitude of 4.5 N·m and is directed in the positive direction of the x axis, and τ2 has a magnitude of 1.4 N·m and is directed in the negative direction of the y axis. What are the magnitude and direction of d/dt, where is the angular momentum of the particle about the origin?

2. A sanding disk with rotational inertia 1.3 10-3 kg·m2 is attached to an electric drill whose motor delivers a torque of 9 N·m about the central axis of the disk. What are the following values about the central axis at the instant the torque has been applied for 140 ms?
(a) the angular momentum of the disk
in kg·m2/s

(b) the angular speed of the disk
in rad/s

  • Physics -

    You failed to mention moment of inertia. I recommend you reread that section, it is what imposes resistance to change of angular motion.

    Torque=momentinertia*alpha (alpha is angular acceleartion, in radians/sec^2)

    Torque*time=momentinertia*change angular velocity

    angular speed final=initialangular speed +alpha*time

    angular displacement=intial angular speed*time+1/2 alpha *Time^2

    MEMORIZE these, understand them. Make flash cards, these are the equations of motion.

    2.a)angular momentum =momentinertia (intial w+alpha*time)
    but alpha=torque/moment of inertia (the first equation you should memorize, above).

    b wfinal=alpha*time

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. whats going on?

    Hi. I posted both the questions about batteries and volatic cells on the last page, who erased it?
  2. Physics - Angular Momentum

    When the angular momentum changes, the 'change' in the angular momentum vector (ie. dL) is ____. [a.] perpendicular to the torque vector. [b.] parallel to the angular momentum vector. [c.] parallel to the torque vector. .. im confused …
  3. math-moneyfractions

    i have some math questions that i really ,really,need help with asap if any body can explain some of these questions that will be great help.Ok here are 3 of the questions i am about to type now ok the first one says,whole 16 nickels …
  4. English

    Does anyone know any good quotes about Jordan Baker and Myrtle Wilson in the Great Gatsby. I only have about 7: "Daisy and Jordan lay upon an enormous couch, like silver idols weighing down their own white dresses against the singing …
  5. Kate

    ok I was doing this problem cos^-1 (0) and was like oh that would be pi/2 but then I thought about it some and decided that even though it's right it can't possibly be... if tan(pi/2) = the first derrivative of a vertical line = undefined …
  6. English

    1. Do you have anything to say about this?
  7. Physics

    A cyclist starts from rest and pedals such that the wheels of his bike have a constant angular acceleration. After 20.0 s, the wheels have made 219 rev. What is the angular acceleration of the wheels?
  8. English

    I need a few characteristic to describe the following: The person quickly switches from loving one person to another.and The person is willing to die for someone even though they have only met for a few days. I thought of a few. But …
  9. physics

    A cyclist starts from rest and pedals such that the wheels of his bike have a constant angular acceleration. After 18.0 s, the wheels have made 190 rev. What is the angular acceleration of the wheels?
  10. physics

    Does the momentum from the arms transfer to the body if you stop it when jumping?

More Similar Questions