Aresearcher would like to perform an experiment in a zero magnetic field, which means that the field of the earth must be canceled. suppose the experiment is done inside a solenoid of diameter 1.0 m, length 3.0 m , with a total of 5000 turns of wire. the solenoid is oriented to produce a field that opposes and exactly cancels the 52 μt local value of the earth's field. what current is needed in the solenoid's wires?

  I = 2.48 10⁻² A

Explanation:

The magnetic field produced by a solenoid disproportionate to the density of turns and the current passing through the wire

        B = μ₀ n I

Where  μ₀ is the magnetic permeability that you are worth 4π 10⁻⁷ N/A²

Let's calculate the density of turns.

        n = N / L

        n = 5000 / 3.0

        n = 1666.67

Let's reduce the field to SI units

      B = 52 μT = 52 10⁻⁶ T

Let's calculate the current

      I = B /  μ₀ n

      I = 52 10⁻⁶ / (4π 10⁻⁷ 1666.67)

      I = 2.48 10⁻² A

this means that the temperature of both substances will be equal

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.