Answer:
The correct option is;
C. The temperature of the air affects the speed of sound
Explanation:
The information given are;
The speed with which sound travels in the desert air = 358 m/s
The speed with which sound travels in the polar air = 330 m/s
The major difference between the desert air and the polar air is that the temperature of the desert air is hotter than the temperature of the air in the polar region. Therefore the speed of sound is affected by the air temperature.
The equation that gives the relationship of the speed of sound in air, 
, to temperature is presented as follows;
Which shows that the speed of sound in air, , rises as the temperature of the air rises.
Where;
= The temperature of the air in degrees Celsius
= The temperature of the air in degrees Kelvin.
Answer:
when the center of gravity is within the washing area, the torque returns in the body to its initial position and is in a stable equilibrium
Explanation:
The concept of center of gravity is equivalent to the concept of center of mass, in this place all external forces applied can be considered.
When we analyze the balance of a body that is the torque it is the one that defines the balance
τ = F xd
If the torque tends to restore the body to the initial position the balance is stable, but if the torque has to increase the body's rotation the balance is unstable
. When the body tends to rotate the torque with respect to the pivot point at the base it decreases because the distance from the center of gravity to the end of the base decreases in value, but it has to return it to the initial position, the balance is stable. The critical point of this process is when the center of gravity is at the limit of the body base area in this case the torque is zero; If the body rotates a little more the center of gravity is outside the base, the torque changes sign and has to increase the turn, going to an unstable balance.
In summary, when the center of gravity is within the washing area, the torque returns in the body to its initial position and is in a stable equilibrium.
D: An electromagnet with 20 coils.
That is because the more coils of the wire, the stronger the electromagnet is.
