Lisa made the electromagnet shown. A nail with wire coiled around it has its head labeled S to the right and its point labeled N to the left. The end of the wire leading to the S is attached to the positive terminal of a battery. The end of the wire leading to the N is attached to the negative terminal of the battery. What can Lisa do to increase the strength of the electromagnet? She can use a nail with weaker magnetic properties. She can change the direction of the nail. She can increase the number of wire loops. She can reduce the current in the wire.

d) physical means can be used to separate the components of air.

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.