Physics

posted by .

A ball (mass m = 250 g) on the end of an ideal string is moving in a circular motion as a conical pendulum. The length L of the string is 1.84 m and the angle with the vertical is 37 degrees.
a) What is the magnitude of the torque (N m) exerted on the ball about the support point?
b) What is the magnitude of the angular momentum (kg m^2/2) of the ball about the support point?

Correct Answers: a) 2.71 b) 1.32

For a I assumed 0 because there wasn't any said force. I do not know how to solve problem.

For b I used L = m*v*r where L = momentum

m = .250 kg
v = (r * g * tan 37 )^(0.5) = (L*sin 37*9.8*tan 37)^(0.5) = 2.8596
r = L * sin 37 = 1.84 * sin 37= 1.10733

Therefore L = .791 This was supposedly incorrect

  • Physics -

    a) The weight exerts a torque about the support point. It equals

    Torque = M g L sin37 = 2.71 N*m^2

    I am using the symbol L for string length

    b) First, get the rotation period P of the ball, using equations derived at
    http://en.wikipedia.org/wiki/Conical_pendulum

    P = 2 pi sqrt(L cos37/g) = 2.43 seconds

    Ball's speed V = 2 pi L sin37/P = 2.86 m/s

    The angular momentum about the support point is M*V*L
    = 0.25*2.86 * 1.84 = 1.32 kg*m^2/s.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Physics

    A bob of mass = 0.250 is suspended from a fixed point with a massless string of length = 23.0 . You will investigate the motion in which the string traces a conical surface with half-angle = 25.0. What tangential speed must the bob …
  2. Physics

    A bob of mass = 0.250 is suspended from a fixed point with a massless string of length = 23.0 . You will investigate the motion in which the string traces a conical surface with half-angle = 25.0. What tangential speed must the bob …
  3. physics

    A bob of mass = 0.250 is suspended from a fixed point with a massless string of length = 23.0 . You will investigate the motion in which the string traces a conical surface with half-angle = 25.0. What tangential speed must the bob …
  4. Physics

    A ball (mass = 250 g) on the end of an ideal string is moving in circular motion as a conical pendulum. The length L of the string is 1.92 m and the angle with the vertical is 37 degrees. A) What is the magnitude of the torque (N m) …
  5. Physics

    A ball (mass m = 250 g) on the end of an ideal string is moving in circular motion as a conical pendulum as in the gure. The length L of the string is 1.67 m and the angle with the vertical is 37 degrees A) What is the magnitude of …
  6. Physics

    A ball on the end of a string is moving in circular motion as a conical pendulum as in the figure. The length L of the string is 1.70 m, the angle  is 37.0 degrees and the ball completes one revolution every 2.51 seconds. (a) What …
  7. Physics Help

    A ball of mass 1.76 kg is tied to a string of length 4.19 m as shown in Figure P6.50. The ball is initially hanging vertically and is given an initial velocity of 9.4 m/s in the horizontal direction. The ball then follows a circular …
  8. Physics

    A ball (mass m = 250 g) on the end of an ideal string is moving in a circular motion as a conical pendulum. The length L of the string is 1.84 m and the angle with the vertical is 37 degrees. a) What is the magnitude of the torque …
  9. Physics

    Consider the conical pendulum, a mass on the end of a string, with the other end of the string fixed to the ceiling. Given the proper push, this pendulum can swing in a circle at an angle q of 25.5 with respect to the vertical, maintaining …
  10. Science

    A uniform metal ball (mass m) is tied to the end of a string (massless, length L). The other end of the string is fixed. The ball is moving in a vertical circle centered at the fixed end of the string. Suppose the velocity of the ball …

More Similar Questions