The first time that astronomers observed both gravitational waves and electro-magnetic waves from the same event, what they were observing was:
a. the merger of two black holes with masses dozens of times the mass of our Sun
b. a supernova explosion in one of the closest galaxies to us
c. the collapse of an entire cluster of stars into one big black hole
d. the spiraling toward each other of two neutron stars
e. a binary star system where a giant star is overloading a white dwarf with too much material

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.

force tends to be low and long diustance masses are high