physics

posted by .

A clothes dryer is spinning at 75 rpm. A student opens its door and it comes to rest after rotating through four revolutions. Assume constant deceleration. What was the magnitude of the dryer's angular deceleration?

  • physics -

    Vi = 75 * 2 pi radians/min *1 min/60 sec
    = 5 pi/2 radians/second

    v = Vi - a t
    0 = 5 pi/2 - a t
    so t = 5 pi/2a

    4*2pi = Vi t + (1/2) a t^2

    8 pi = ( 5 pi/2)(5 pi/2a) + (1/2)a (5 pi/2a)^2

    etc

  • sign repair -

    Vi = 75 * 2 pi radians/min *1 min/60 sec
    = 5 pi/2 radians/second

    v = Vi - a t
    0 = 5 pi/2 - a t
    so t = 5 pi/2a
    +++++++++ a is assumed negative +++
    4*2pi = Vi t - (1/2) a t^2

    8 pi = ( 5 pi/2)(5 pi/2a) - (1/2)a (5 pi/2a)^2

    8 pi a = (5 pi/2)^2 = (1/2)(5 pi/2)^2

    8 pi a = (1/2)(5 pi/2)^2
    16 pi a = 25 pi^2/4
    a = (25/64) pi
    remember it is negative (deacceleration)

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. college physics

    The blade in a food processor spins at 1700 rpm. After the machine is turned off, the blade comes to a stop in 3.7s. How many revolutions does it make during this time, assuming constant angular deceleration?
  2. physics

    A luge and its rider, with a total mass of 84 kg, emerge from a downhill track onto a horizontal straight track with an initial speed of 41 m/s. Assume that they stop with a constant deceleration of 3.5 m/s2. (a) What magnitude F is …
  3. Physics

    A clothes dryer undergoes an centripetal acceleration of 28m/s^2 if the dryer has a radius of 27cm what is the trangential speed of a sock struck to the outside of the dryers rotating barrel?
  4. physics

    A clothes dryer is spinning at 75 rpm. A student opens its door and it comes to rest after rotating through four revolutions. Assume constant deceleration. What was the magnitude of the dryer's angular deceleration?
  5. Physics

    A centrifuge is a common laboratory instrument that separates components of differing densities in solution. This is accomplished by spinning a sample around in a circle with a large angular speed. Suppose that after a centrifuge in …
  6. physics

    A centrifuge is a common laboratory instrument that separates components of differing densities in solution. This is accomplished by spinning a sample around in a circle with a large angular speed. Suppose that after a centrifuge in …
  7. physics

    An automatic dryer spins wet clothes at an angular speed of 4.4 rad/s. Starting from rest, the dryer reaches its operating speed with an average angular acceleration of 4.2 rad/s2. How long does it take the dryer to come up to speed?
  8. Science 8th Grade

    Items of clothing rub against each other when they are in a clothes dryer. This can sometimes cause a person to feel a slight shock when he or she removes the clothes from the dryer. This is due to A. The dryer not being grounded B. …
  9. Tobias

    If a rotating disk starts from rest and ends up at 200 rpm in 4 seconds, what is the angular acceleration?
  10. physics

    help please?? A bocce ball with a diameter of 6.00 cm rolls without slipping on a level lawn. It has an initial angular speed of 2.35 rad/s and comes to rest after 2.50 m. Assuming constant deceleration, determine (a) the magnitude

More Similar Questions