Answer:
Explanation:
Magnetic Force on the rod F = Bi L
Work done by this force = F X d
= Bi Ld
This energy is converted into both rotational and linear kinetic energy
= 1/2 I ω² + 1/2 mv²
= 1/2 x 1/2 m r²ω²+ 1/2 mv²
= 1/4 m v² + 1/2 mv²
= 3/4 mv²
So according to conservation of energy
Bi Ld = 3/4 mv²
v = 
The frequency produced by the string could be 437 Hz or it could be 443 Hz.
The frequency of the beats ... 3 Hz ... tells the piano tuner that
the difference between the fork and string frequencies is 3 Hz,
but it doesn't tell her which one is higher or lower.
Answer:
Read below!
Explanation:
You can watch the sun wheel across the sky during the day, and the stars at night. Focus a telescope on any star besides the north star--especially southern stars--and you can watch them drift across your field of view.
An alternative explanation is that all the stars are painted on (or holes in) some canopy that rotates around the earth. This explanation does not account for the motion of the "wanderers," or planets, as the Greeks called them, or for the path of the moon among the stars.
As we know the stars are massive bodies of significant and varying distance to the earth, the notion they all swing around us in unison seems highly implausible
Different densities have to have a reason - different pressure and/or humidity etc. If there is a different pressure, there is a mechanical force that preserves the pressure difference: think about the cyclones that have a lower pressure in the center. The cyclones rotate in the right direction and the cyclone may be preserved by the Coriolis force.
If the two air masses differ by humidity, the mixing will almost always lead to precipitation - which includes a phase transition for water etc. It's because the vapor from the more humid air mass gets condensed under the conditions of the other. You get some rain. In general, intense precipitation, thunderstorms, and other visible isolated weather events are linked to weather fronts.
At any rate, a mixing of two air masses is a nontrivial, violent process in general. That's why the boundary is called a "front". In the military jargon, a front is the contested frontier of a conflict. So your idea that the air masses could mix quickly and peacefully - whatever you exactly mean quantitatively - either neglects the inertia of the air, a relatively low diffusion coefficient, a low thermal conductivity, and/or high latent heat of water vapor. A front is something that didn't disappear within minutes so pretty much tautologically, there must be forces that make such a quick disappearance impossible.
