A mysterious force has been discovered in nature that acts on all particles in the three-dimensional space. You determine that the force is always pointed away from a definite point in space, which we can call the force center. The magnitude of the force turns out to be proportional to 1/r4, where r is the distance from the force center to any other point. Your friend says that it has been determined that the constant of proportionality has been determined to be 2 (in units to be determined), i. e. the magnitude of the force on a particle can be written as 2/r4, when the particle is at a distance r from the force center.

spectral lines lyman is one set

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.

the answer you are looking for is d. there are no holes for blood to enter or leave the system. your welcome