Answer:
A. The upward pressure gradient force is balanced by gravity.
Explanation:
A. is correct because the pressure difference is actually generated by gravity. As in the following formula for the pressure at different points:
where 
are the pressure at 2 points, ρ is the density of the fluid, g is the gravitational constant, and h is the height difference.
B is incorrect because friction in air is too small to make an effect.
C is incorrect because the Coriolis force is horizontal, not vertical.
D is incorrect because a difference of 500 hPa = 50000 Pa, this is half of the atmospheric pressure.
E is incorrect because temperature cannot generate force.
<u>Question:</u>
You are working on an experiment involving a very strong permanent magnet, and your data suggests that your magnet's field suddenly decreased during some interval in time. Such a decrease could have been caused by the magnet
A. Having overheated substantially
B. Being hit hard
C. Both A and B
D. Being grounded out
<h3><u>Answer:</u></h3>
A decrease in magnetic field of the permanent magnet have been caused by the magnet having overheated substantially or sharp impacts by being hit hard.
Option c
<h3><u>Explanation: </u></h3>
Permanent magnets are ferromagnetic materials with its magnetic domains aligned and grouped together in the same direction. These atomic domains maintain their directionality and hence a permanent magnet provides persistently strong magnetic fields without quick weakening. Some factors may lead to demagnetization or else a consistent reduction in magnetic strength.
Overheating a magnetic material realigns the magnetic domain regions and affects its directionality. When it reaches to a temperature defined as Curie temperature, varying with each material; the substance is no more a magnet due to complete randomness in the domain structure. As the temperature decreases and approaches the room temperature, magnetic field appears but is less in strength. Sudden impacts due to hitting may lead to random realignment of magnetic domains and thus decrease its magnetic strength.
I don't understand this question
Answer:
True statements:
Power is the rate at which work is done.
Power is the rate at which energy is transformed.
The SI unit of power is watt.
A person is limited in the total work he or she can do by the rate at which energy can be transformed.
Explanation:
The above statements are true.
1. Power is defined as the rate at which work is done.
2. Power is the rate at which energy is transformed. Whenever energy changes its form, or moves from one place to another, the rate at which it makes those changes is described as power.
3. The SI Unit of power is watts. If 1 joule of energy is converted by an object in 1 second then its power is called one watt.
So, the statement<em> 'the SI unit of power is the horsepower' is</em> false.
4. A person is limited in the total work he or she can do by the rate at which energy can be transformed i.e, his power. He is not only limited by the total energy required.
So, the statement <em>'A person is limited in the total work he or she can do only by the total energy required'</em> is not completely true.
