Mar 27, 2017

The force changes the most in terms of value and the type of force, however, in terms of numerical value, it is acceleration.

#### Explanation:

The mass of an object is the amount of matter in it. This never changes unless you change the matter. E.g. an acorn that measures $2 g$ on a tree branch will measure $2 g$ on the floor.

Therefore, we can eliminate that option.

Forces are essentially a push or pull on an object. Forces vary from a weak force applied to a strong force, depending on the amount of strength applied at a distance/direct contact. In this case, the acorn that is hanging on the tree branch has gravitational force, ${F}_{\text{g}}$, pulling it down, and the force of tension, ${F}_{\text{T}}$, pulling it up.

When it falls, the force changes to that of motion. The ${F}_{\text{g}}$ that was supposedly equal to the ${F}_{\text{T}}$, is now unbalanced. ${F}_{\text{T}}$ has been converted to air resistance (friction), ${F}_{\text{F}}$, and is not strong enough to keep the acorn from falling. The ${F}_{\text{g}}$ overpowers the ${F}_{\text{F}}$, and causes the acorn to fall. Though the force of gravity stays the same, the net force, ${F}_{\text{NET}}$, changes.

This is most likely the correct answer, but I'll go over the other options to double check.

Density is a unit of measurement, measuring the amount of mass in a given volume. Stated before, the mass of the acorn does not change. The volume also does not change (unless it falls and breaks and pieces are detached).

Therefore, we can rule out density.

Lastly, we have acceleration. The acceleration of an object that is suspended is subject to gravitational acceleration, despite not moving.

As the acorn falls, the acceleration remains constant, but the speed increases. DO NOT CONFUSE THIS WITH SPEED/VELOCITY. There is a large difference between the two and I highly recommend you understand how to differentiate between the two.

As a result, we dismiss acceleration.

After going over every possibility, we can conclude that when the acorn falls, its (net) force will change (the most).

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Another way to interpret the question is to view it as which of the 4 changes the most numerically. In this case, acceleration is the answer because once the acorn stops falling, the acceleration changes from $9.8 \frac{m}{s} ^ 2 \left[\text{down}\right]$ to $0 \frac{m}{s} ^ 2 \left[\text{down}\right]$.

The force changes the most in terms of value and the type of force, however, in terms of numerical value, it is acceleration.

Hope this helps :)