Classical Mechanics Physics

A yoyo of mass m=2 kg and moment of inertia ICM=0.09 kg m2 consists of two solid disks of radius R=0.3 m, connected by a central spindle of radius r=0.225 m and negligible mass. A light string is coiled around the central spindle. The yoyo is placed upright on a flat rough surface and the string is pulled with a horizontal force F=24 N, and the yoyo rolls without slipping.

(a) What is the x-component of the acceleration of the center of mass of the yoyo? (in m/s2)

a=

(b) What is the x-component of the friction force? (in N)

f=

  1. 👍 0
  2. 👎 0
  3. 👁 257
  1. :/ What did you do so far? Also, we're not really going to solve all your problems for you you have to at least make an effort

    1. 👍 0
    2. 👎 0
  2. I solved the problem this way:

    Using F = ma, and the given, I had F - friction force = ma, with friction force = 22 - 2a. With torque = I*alpha, I got 0.25*friction force - 0.1875*22 = 0.0625*alpha.

    To put them all together, I got this equation, R(22-2a) - 0.1875*22 = (0.0625/0.25)*a
    And then plugging the given, I got a = 1.83 m/s^2, but I don't think I'm doing this correctly.

    Can someone please help me figure out where I went wrong right away. Thanks so much...

    1. 👍 0
    2. 👎 0
  3. alpha isnt the same as a

    1. 👍 0
    2. 👎 0
  4. y u don't say???

    a= F*R(1-(r/R))/((I/R)+(m*R)) is correct or not!

    1. 👍 0
    2. 👎 0
  5. No it is not correct.

    1. 👍 0
    2. 👎 0
  6. then is this correct
    a=[F*(R+r)]/[(l/R)+m*R)]
    and friction f
    f = force - m*a??

    1. 👍 0
    2. 👎 0
  7. Yes a is correct. f is correct, you will get negative answer but input it positive. Tell me if it worked for you

    1. 👍 0
    2. 👎 0
  8. Hi enjoy. I tried F=force - m*a = 22-(2*12.8333) =
    -3.6666 in the negative x direction. I am down to my last chance. Like with all the problems. Thanks, I am trying to keep my head above water. I still have a long way to go. I also had trouble with Question no. 1.

    1. 👍 0
    2. 👎 0
  9. You should get a negative answer, this means the friction is acting in the opposite way that the diagram shows therefore you must input it as positive!!!

    Also how did you do on question 8!

    1. 👍 0
    2. 👎 0
  10. It might be better to indicate the equation rather than answers, because the data changes. So, we have:
    F-ff=ma (1)
    I.alpha=F.R-ff.r (2)

    and we have two equation ant variables.
    but alpha is a/R or a/r

    1. 👍 0
    2. 👎 0
  11. error, so we'll have:
    F-ff=m.a -> ff=F-m.a (1)

    I.alpha=F.r+ff.R (2)
    alpha=a/R

    then:
    a=F.(R+r)/(I/R+m.R)

    a=positive
    ff=negative, and for a got green mark, but not for f, should I write ff with "-" or just the value?

    I got a=16.3 f=-4.6

    1. 👍 0
    2. 👎 0
  12. Hi Geoff, Thanks for the tip. I would have entered it as entered my answer as -3.666. I entered as positive 3.666 and it was correct. Good call.

    1. 👍 0
    2. 👎 0
  13. my values were right, just had to write the value of f without the -.

    Now, anyone has checked the falling ruler???

    1. 👍 0
    2. 👎 0
  14. Whats your method for the falling ruler?

    1. 👍 0
    2. 👎 0

Respond to this Question

First Name

Your Response

Similar Questions

  1. Physics

    M, a solid cylinder (M=2.35 kg, R=0.111 m) pivots on a thin, fixed, frictionless bearing. A string wrapped around the cylinder pulls downward with a force F which equals the weight of a 0.750 kg mass, i.e., F = 7.357 N.

  2. Physics

    A hollow sphere has a mass of 15 kg, an inner radius of 12 cm and an outer radius of 18 cm. What is the rotational inertia (moment of inertia) of the sphere about an axis passing through its center?

  3. astronomy

    Rank the following hypothetical planets -- all of which have the same total mass and same radius -- from lowest moment of inertia to highest moment of inertia: 1) A uniform sphere of mixed up rock and iron 2) A rocky planet with

  4. Physics

    . (a) Calculate the angular momentum of an ice skater spinning at 6.00 rev/s given his moment of inertia is 0.400 kg ⋅ m2. (b) He reduces his rate of spin (his angular velocity) by extending his arms and increasing his moment of

  1. Please check solution

    A uniform solid disk with a mass of 40.3 kg and a radius of 0.454 m is free to rotate about a frictionless axle. Forces of 90.0 N and 125 N are applied to the disk (a) What is the net torque produced by the two forces? (Assume

  2. physics

    A student sits on a freely rotating stool holding two weights, each of which has a mass of 3.00 kg. When his arms are extended horizontally, the weights are 1.00 m from the axis of rotation and he rotates with an angular speed of

  3. Chemistry

    The general formula for moment of inertia is: I = Sigma mi * ri^2 (mi is mass of atom, ri is distance to axis of rotation) In a diatomic molecule, the moment of inertia is I = ma*mb(ma+mb) * R^2 (R is distance between atoms, ma

  4. Physics

    1- Suppose a bicycle wheel is rotated about an axis through its rim and parallel to its axle. Is its moment of inertia about this axis greater than, less than, or equal to its moment of inertia about its axle? a. less than b.

  1. Physics

    What is the moment of inertia of an object that rolls without slipping down a 2.00-m-high incline starting from rest, and has a final velocity of 6.00 m/s? Express the moment of inertia as a multiple of MR2, where M is the mass of

  2. physics

    An oxygen molecule consists of two oxygen atoms whose total mass is 5.3 x 10-26 kg and whose moment of inertia about an axis perpendicular to the line joining the two atoms, midway between them, is 1.82 × 10-46 kg·m2. From these

  3. Physics

    A 4.0-kg mass is placed at (3.0, 4.0) m, and a 6.0-kg mass is placed at (3.0, -4.0) m. What is the moment of inertia of this system of masses about the x-axis?

  4. physics

    A spool of thin wire pivots on a shaft with friction. The wire is pulled by a hanging mass M=1.50 kg. Upon starting from rest and falling a distance D=1.65 m, the mass has a speed V=2.00 m/s. Calculate the energy lost to friction

You can view more similar questions or ask a new question.