Fundamental Forces
Electromagnetic Force
A force between electrically charged particles. The second strongest of the fundamental forces; it can be either attractive or repulsive.
Nuclear Strong Force
A force between quarks that binds quarks of different "colors" together to form protons and neutrons and holds the nuclei of atoms together in spite of the protons electrostatic repulsion. It is the strongest of the fundamental forces but acts only across very short distances.
Weak Force
A force involved in radioactive decay; it can change an up quark into a down quark, thereby changing a proton into a neutron, or vice versa.
The Law of Universal Gravitation
All objects with mass attract all other objects with mass with a force that is directly proportional to the objects' masses and inversely proportional to the square of the distance between them.
Gravitational Force
An attractive force between all objects with mass; the weakest of the fundamental forces
Who experimentally calculated the Gravitational Constant?
Cavendish
The Law of Conservation of Charge
Charge cannot be created or destroyed, only transferred; when two objects interact, the total charge of the system remains the same
electron
Electrons reside outside of the atom's nucleus. They have a charge of -1 and have very little mass.
Quarks
Elementary (we think!) particles that make up protons and neutrons (among other things)
How do the number of protons and electrons compare in a neutral atom?
In a neutral atom the number of protons and electrons are equal.
neutron
Neutrons reside in the atom's nucleus. They consist of two down quarks and one up quark. They have no charge and are relatively massive (compared to an electron).
Who discovered the Law of Universal Gravitation?
Newton
Coulomb's Law
Objects with like charges repel, and objects with unlike charges attract with a force that is directly proportional to the charges of the objects and inversely proportional to the distance between the objects squared.
proton
Protons reside in the atom's nucleus. They consist of two up quarks and one down quark. They have a charge of +1 and are relatively massive (compared to an electron).
If a neutral atom becomes negative, what must have happened?
The atom must have gained one or more electrons.
If a neutral atom becomes positive, what must have happened?
The atom must have lost one or more electrons.
If you rub two neutral objects together and generate an electric charge, what do you know about the charges on the two objects?
The objects must have equal and opposite charges. The net charge on the system was zero to begin with and must remain zero according to the Law of Conservation of Charge.
Would a positively charged object and a negatively charged object attract or repel?
They would attract. (Opposites charges attract.)
Would a negatively charged object and another negatively charged object attract or repel?
They would repel. (Like charges repel.)
Would a positively charged object and another positively charged object attract or repel?
They would repel. (Like charges repel.)
According to the Law of Universal Gravitation, the force of gravity is _______________ proportional to the mass of the objects.
directly
According to the Law of Universal Gravitation, the force of gravity is _______________ proportional to the *square* of the distance between the two objects.
inversely
Name the four Fundamental Forces from strongest to weakest
the Nuclear Strong Force, the Electromagnetic Force, the Weak Force, the Gravitational Force
nucleus
the center of the atom - the nucleus contains almost all of the mass of the atom but only constitutes a tiny fraction of the atom's volume (not to be confused with the nucleus of a cell!)
electron cloud
the part of an atom occupied by the electrons; the electron cloud, which constitutes the vast majority of the atom's volume, is almost entirely empty space.
atom
the smallest unit of an element, the building block of matter
subatomic particles
the three particles that make up an atom -- protons, neutrons, and electrons
