At the security area of an airport, you walk through a weak AC magnetic field inside a coil of wire. What is the result of a small piece of metal on your person that slightly alters the magnetic field in the coil?Answer

A. Temperature differences are induced in the metal that can be detected by the coil of wire, this in turn changes the AC current in the coils and sets off an alarm.
B. Radiation is induced in the metal that can be detected by the coil of wire, this in turn changes the AC current in the coils and sets off an alarm.
C. Electric currents are induced in the metal that changes the magnetic field, this in turn changes the AC current in the coils and sets off an alarm.

0.11 m/s and 0.28 m/s should be correct

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.