Friday, October 30, 2009

Assignment for Friday, 10-30-09

Log onto a computer with your group.
On the Novell Screen go to:

Interactive Journey Through Physics
–Circular Motion 1
–Circular Motion 2
Do all parts except MCAT Questions

Submit one set of answers for the group. You can submit by paper, or copy/paste to the comment section below (just do it as an anonymous poster).

1 comment:

  1. Kevin I. Hazel M. Yoshika W.

    Circular Motion 1.
    problem 1:
    A conical pendulum consists of a 380-g bob attached to a string 35-cm long that makes an angle of 15 degrees with the verticle. What is the centripetal force acting on the bob?
    Answer: .998

    Problem 2:
    a ball of mass .1kg moves in a circle of radius .2m with a constant speed of 4m/s. Acceleration?

    Problem 3:
    A ball moves in a circle of radius 1 m at a constant speed. The period of motion is 2 seconds. What is the speed of the ball?
    Answer:π m/s

    Problem 4:
    The ride in question has a 44.5 N chiar which hangs freely from a 9.14 m long chain attached to a pivot on the top of a tall tower. When a child enters the ride, the chain is hanging straight down. The child is then attached to the chair with a seat belt and shoulder harness. When the ride starts up,the chain rotates about the tower. Soon the chain reaches its max. speed and remains rotating at that speed. It rotates about the tower once every 3.0 seconds. When you ask the operator, he says that the ride is perfectly safe. He demonstrates this by sitting in the stationary chair. The chain creaks but holds and he weighs 890 N. Has the operator shown that this ride is safe for a 222.5 N child?
    Answer: No, he has not shown that it is safe and the child should not ride.

    Circular motion 2
    Problem 1:
    a wheel is set into motion so that it experiences a constant angular acceleration of .2rad/s. If it starts from rest, what is its angular displacement after 5 seconds?
    Answer: 143.2 degrees

    Problem 2:
    A ball moves in a circle with a radius of 15cm. Its angular displacement is given by θ=2t^2. Assume that it starts from rest. What is its angular acceleration?
    Answer:4 rad/s^2

    Problem 3:
    A solid rotating ball has an angular velocity about an axis through its center of 8 rad/s when it is acted upon by a force. This force gives the ball an angular acceleration of 1 rad/s for 4 seconds. By what factor is its kinetic energy increased?