Physics

Two uniform solid spheres have the same mass of 3 kg, but one has a radius of 0.25 m while the other has a radius of 0.8 m. Each can rotate about an axis through its center.

(a) What is the magnitude τ of the torque required to bring the smaller sphere from rest to an angular speed of 300 rad/s in 15 s?
N·m

(b) What is the magnitude F of the force that must be applied tangentially at the sphere's equator to provide that torque?
N

(c) What is the corresponding value of τ for the larger sphere?
N·m

(d) What is the corresponding value of F for the larger sphere?
N

  1. 👍
  2. 👎
  3. 👁
  1. I sphere = (2/5) mR^2
    see http://hyperphysics.phy-astr.gsu.edu/hbase/isph.html

    I1 = (2/5)3 (.25)^2 = .075
    alpha = 300/15 = 20 radians/second^2
    Torque = I alpha = .075*20 = 1.5 Nm

    F1 = torque/R = 1.5/.25 = 6 N

    now big sphere
    I2 = (2/5)3 (.8)^2 = .768
    torque = I alpha = .768*20 = 15.36 Nm
    F2 = 15.36/.8 = 19.2 N

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. electric field intensity

    Two 2.0 g spheres are suspended by 10.0 cm long light strings. A uniform electric field is applied in the x direction. If the spheres have charges of -5.0 10-8 C and +5.0 10-8 C, determine the electric field intensity that enables

  2. Physics

    Two spheres are cut from a certain uniform rock.One has radius 4.50 cm.The mass of the other is five times greater. Find its radius.

  3. physics

    A bowling ball (mass = 7.2 kg, radius = 0.12 m) and a billiard ball (mass = 0.31 kg, radius = 0.028 m) may each be treated as uniform spheres. What is the magnitude of the maximum gravitational force that each can exert on the

  4. physics

    A uniform solid cylinder of radius R and a thin uniform spherical shell of radius R both roll without slipping. If both objects have the same mass and the same kinetic energy, what is the ratio of the linear speed of the cylinder

  1. Physics

    Consider three identical metal spheres, A, B, and C. Sphere A carries a charge of -8q. Sphere B carries a charge of +7q. Sphere C carries no net charge. Spheres A and B are touched together and then separated. Sphere C is then

  2. general chemistry

    What is the radius of the largest sphere that can be placed at the center of a face-centered cubic unit cell of a cubic closest-packed array of spheres if the spheres have radius of 2.0 x 10^2 pm?

  3. Physics

    A solid, uniform, frictionless cylindrical reel of mass M = 3.00 kg and radius R = 0.400 m is used to draw water from a well.? A bucket of mass m = 2.00kg is attached to a cord that is wrapped around the cylinder. (a) Find the

  4. Physics

    Two spheres are cut from a certain uniform rock. One has radius 3.54 cm. The mass of the other is 3 times greater. Find its radius.

  1. Physics

    Three uniform spheres of masses m1 = 3.50 kg, m2 = 4.00 kg, and m3 = 6.50 kg are placed at the corners of a right triangle (see figure below). Calculate the resultant gravitational force on the object of mass m2, assuming the

  2. Physics

    Three uniform spheres are located at the corners of an equilateral triangle. Each side of the triangle has a length of 2.50 m. Two of the spheres have a mass of 4.40 kg each. The third sphere (mass unknown) is released from rest.

  3. physics concepts (please check over my work)

    A uniform cyclinder made of lead has the same mass and the same length as a uniform solid cylinder made of wood. The rotatonal inertia of the lead cylinder compared to the wooden one is: I thought at first that the rotational

  4. mathematics

    Three uniform small spheres A, B and C have equal radii and masses 3 m, m and m respectively. The spheres are at rest in a straight line on a smooth horizontal surface, with B between A and C. The coefficient of restitution

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