Answer:
Friction force is 0.1375 N
Solution:
As per the question:
Radius of the metal disc, R = 4.0 cm = 0.04 m
Magnetic field, B = 1.25 T
Current, I = 5.5 A
Force on a current carrying conductor in a magnetic field is given by considering it on a differential element:
Integrating the above eqn:
(1)
Now the torque is given by:
(2)
From eqn (1) and (2):
Thus the Frictional force is given by:
Answer:
<em>The ball has 7.35 joules of energy at position B.</em>
<em>The velocity of the ball at position A is 3.13 meter/second</em>
Explanation:
<u>Kinetic and Gravitational Potential Energy</u>
Kinetic energy is the form of energy that an object or a particle has by reason of its motion. An object of mass m and speed v has kinetic energy calculated by:
Gravitational Potential Energy is the form of energy that an object has by reason of its height h relative to a certain reference. It can be calculated as follows:
Where g is the acceleration of gravity.
The figure shows a pendulum with a bob (ball) of mass m=1.5 Kg. When it's pulled to point B, it has a height of h= 0.5 m and set to rest.
The potential energy at that point is:
The ball has 7.35 joules of energy at position B.
When the ball is released, all of the potential energy is transformed into kinetic energy when reaches point A. Thus:
K=7.35 J
From the equation of kinetic energy, we solve for v:
v = 3.13 m/s
The velocity of the ball at position A is 3.13 meter/second