need answer for 2, 3 1. If centripetal force, F c , is constant and radius, r ,

Question

need answer for 2, 3

1. If centripetal force, Fc, is constant and radius, r, increases, state whether, and explain why, angular velocity, , increases or decreases with increasing r.

f= mrw^2

NOTE: The following questions ask about the same physical phenomenon and how we are going to measure it. They ask the same question differently to aid your understanding.

BACKGROUND:

     Newton’s Second Law: F = m x a. The net force acting on a body, also called the resultant force,

     is the vector sum of all forces acting on the body.

1. Observe the horizontal disk with the steel ring in Figure 10.3. There is a string wrapped around a torque pulley beneath the disk. The string is passed over a pulley and the other end of the string is connected to a mass hanger with a mass. The total mass of the hanger and mass is 0.0053kg. This hanger experiences a force due to gravity of

               9.800(m/s2) x 0.0053(kg) = 0.052(N)

The string transmits this force tangentially to the edge of the torque pulley. The disk is turning at a constant rate. That means the angular velocity is constant. State why the disk and ring are not accelerating under the influence of the force exerted by gravity on the hanging mass. State what physical phenomenon is preventing the disk and ring from accelerating.

2. In this experiment ( centripetal force and rotational inertia ) we will gradually add very small masses to the mass hanger and give the disk a small push to overcome static friction, and to start the disk turning, in the direction that causes the mass hanger to fall. Capstone will measure the linear velocity of the string and plot this velocity versus time. The acceleration due to gravity times the mass on the end of the string (hanger plus added masses) is the force acting to accelerate the disk. We will keep adding mass to the hanger until when we give the disk a small push the disk turns at a constant angular velocity without accelerating. We know the force on the mass and hanger that is trying to accelerate the disk. If the disk is not accelerating, but turning at a constant velocity, what additional force on the disk do we now know the value of?

What is this additional force equal to?

3. Using the disk only, without the steel ring, we will place .1000 kg on the hanger, release the hanger and determine the linear acceleration of the falling mass. Gravity acts on the hanging mass. A string is passed over a pulley and transmits the force on the hanging mass to the torque pulley attached to the disk. Gravity acting on the hanging mass and the tension in the string act to accelerate the disk. Is this the only force acting? If not, how will we determine the other force on the disk?

Explanation / Answer

Answering 2nd question

If net force is zero,then only the disc will rotate with angular accleration=0

So net force on disc=0

We need to apply force =mg where m is mass of hanger mass .Then net force=0 so extra force =mg

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