The impulse-momentum theorem
Answer:
A compass works by detecting and responding to the Earth's natural magnetic fields. The Earth has an iron core that is part liquid and part solid crystal, due to gravitational pressure. It is believed that movement in the liquid outer core is what produces the Earth's magnetic field.
Explanation:
Answer:
Part(a): The final angular velocity is 
Part(b): The ratio of the rotational energies is
,showing the the energy of th system will decrease.
Explanation:
Part(a):
If '
' be the moment of inertia of an object and '
' be its angular velocity then the angular momentum '
' of the object can be written as

If '
' and '
' be the moment of inertia of the two cylinders and '
' and '
' be the initial angular velocity of the cylinders and '
' and '
' be their respective final angular velocity, then from conservation of angular momentum,

Given,
. From the above expression

Part(b):
Initial kinetic energy
and Final kinetic energy

Substituting the value of
,

The above expression shows that the ebergy of the system will decrease.
If you pack more mass into a certain volume, the density will increase.
<span>A
sound wave is a pressure wave that results from the vibration of the particles
o the medium from the source. The motion of the particles in the medium is
parallel to the direction of the energy transport. The type of wave formed by a
sound wave is the longitudinal wave. </span>A longitudinal wave is
characterized by rarefactions. A longitudinal wave is a wave motion wherein the
particles in the wave medium are displaced parallel to transport. When motion
is detected from the source, the particle next to it vibrates from its rest
position and a progressive change in phase vibration is observed at each
particle within that wave. The result is that the energy is transported from
one region to the other. These combined motions result in the movement of
alternating regions of rarefaction in the direction of propagation.