A wheel with rotational inertia I is mounted on a fixed, fricitonless axle. The angular speed w of the wheel is inccreased from zero to w_f in a time interval T.
1: What is the average net torque on the wheel during the time interval, T?
a) w_f/T
c) Iw_f^2/T

I know that torque equals rFsin theda and r=sqrt(I/m). Is the answer e)?

2: What is the average power input to the wheel during this time ineterval T?
a) Iw_f/2T

what is the equation for power? I don't get this part of the problem... If i had to guess would the answer be b)?

Your reasoning on 1 baffles me. What is avg angular acceleration: wf/T.

Torque= I *angular acceleration

Power? Work= Torque*angular displacement
but angular displacement= 1/2 angacc*time^2

Power= work/time= I*wf/T*1/2*wf/T*T

work it out, and check that.

  1. 👍 1
  2. 👎 2
  3. 👁 4,644
  1. okay so P=W/t
    so the force is the torque from the first problem and you need to find the d
    ang. acc. = wf/t
    so you use that to plug into the formula: wf^2= wi + 2(alpha)(d)
    change wi to zero
    and substitue wf/t into alpha and solve for d
    use that as the d for Fxd/T and you'll get

    1. 👍 2
    2. 👎 0
  2. We know work is increase or decrease in energy. During this time period the wheel gains kinetic energy K = (1/2)Iwf^2. So that is the work done. power = work/time so the kinetic energy expression over T resulting in Iwf^2/2T

    1. 👍 2
    2. 👎 0
  3. My girl Teresa out here responding 9 years later

    1. 👍 35
    2. 👎 0

Respond to this Question

First Name

Your Response

Similar Questions

  1. Physics

    A small disk of radius R1 is mounted coaxially with a larger disk of radius R2. The disks are securely fastened to each other and the combination is free to rotate on a fixed axle that is perpendicular to a horizontal frictionless

    asked by John on December 2, 2011
  2. Physics

    A potter’s wheel with rotational inertia of 45 kg m2, is spinning freely at 40 rpm. The potter drops a lump of clay onto the wheel where it sticks a distance 1.2 m from the rotational axis at the wheel’s center. If the

    asked by Sarah on June 29, 2009
  3. physics

    A bicycle has wheels of radius 0.3 m. Each wheel has a rotational inertia of 0.088 kg× m2 about its axle. The total mass of the bicycle including the wheels and the rider is 79 kg. When coasting at constant speed, what fraction

    asked by alicia on July 10, 2012
  4. physics

    A small rubber wheel is used to drive a large pottery wheel, and they are mounted so that their circular edges touch. The small wheel has a radius of 1.7 cm and accelerates at the rate of 6.9 rad/s^2, and it is in contact with the

    asked by rob on October 18, 2010
  5. Physics

    A man stands on a platform that is rotating (without friction) with an angular speed of 1.21 rev/s; his arms are outstretched and he holds a brick in each hand The rotational inertia of the system consisting of the man, bricks,

    asked by Aimee on November 18, 2011
  1. physics

    The speed of a moving bullet can be determined by allowing the bullet to pass through two rotating paper disks mounted a distance d apart on the same axle (Fig. below). From the angular displacement of the two bullet holes in the

    asked by Anonymous on May 18, 2013
  2. 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.

    asked by MUHAMMAD JUNAID on April 12, 2019
  3. physics

    A bicycle wheel is mounted on a fixed, frictionless axle. A massless string is wound around the wheel's rim, and a constant horizontal force, F, starts pulling the string from the top of the wheel starting at time t = 0 when the

    asked by Gabe on January 22, 2010
  4. physics

    A 4.00-m length of light nylon cord is wound around a uniform cylindrical spool of radius 0.500 m and mass 1.00 kg. The spool is mounted on a frictionless axle and is initially at rest. The cord is pulled from the spool with a

    asked by Mike on March 19, 2012
  5. Physics

    A Texas cockroach of mass 0.17 kg runs counterclockwise around the rim of a lazy Susan (a circular disk mounted on a vertical axle) that has radius 15 cm, rotational inertia 5.5 10-3 kg·m2, and frictionless bearings. The

    asked by Ray on October 26, 2009

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