phinds said:
Of the four, we experience only gravity directly so we don't think of the others in terms of what "seems" to be the case.
I would say that there are two of the forces that we, as humans, experience on a day to day basis (even people without a scientific background): Gravity and the electromagnetic force.
Gravity is obvious. But the electromagnetic force, together with the Pauli exclusion principle, affect our lives all the time.
First I should mention that the Pauli exclusion principle is not a force. It's a principle that states that no two Fermions can occupy the same quantum state at the same time. It's what keeps an atom's electrons in their orbital "shells" (so to speak; more on that maybe another time) rather than all collapse together into the lowest allowed energy level. It gives rise to atoms' valance states. It's not limited to electrons though, it also keeps particles that make up the atom's nucleus separated from each other.
Now, taking the Pauli exclusion principle as a given, the force that keeps you from falling through the ground to the center of the Earth is the electromagnetic force. Yes, that Normal force that counteracts the gravitational force, thus keeping you on your feet, is the electromagnetic force. It's the electromagnetic forces acting between the atoms on the ground and the atoms on the bottom of your shoes.
If you grab a wooden meter stick and try to pull it apart, you'll find it isn't easy. That force keeping it together is also the electromagnetic force. Pretty much the force that causes any solid object to keep its shape is the electromagnetic force.
Pretty much the whole of chemistry is all based on the electromagnetic force. (And by extension, biology.) At its fundamental level, how do you explain what happens when you combine an acid with a base? Yep, the electromagnetic force. How do atoms fit together into molecules. Yep, electromagnetic force.
It goes without saying that electric motors and generators, current flowing through wires, and the electronics you are using to read this sentence all involve the electromagnetic force.
Ever light a match? Electromagnetic force.
Digesting food? Electromagnetic force.
The strong and weak nuclear forces are much more nuanced (aka. complicated). Most people don't knowingly experience those in such a way as to see them in action. 'Not without fancy instrumentation anyway. [Edit: Smoke detectors exploit the weak nuclear force, as well as some other common items that I can't think of right now. They're not as everyday common as the electromagnetic force though.]
[Another edit: Oh, the Sun's core undergoes fusion, which involves the strong and weak nuclear forces. So there's that. But we don't see that directly. By the time the energy reaches the Sun's photosphere, all the energy is tied up in electromagnetic forces, which is what we see as sunlight (photons are carriers of the electromagnetic force).
The cores of nuclear power plants involve the nuclear forces, obviously. So those too.]
