The document describes the four fundamental forces that govern interactions between matter: (1) the strong force that binds quarks together and holds protons and neutrons in the atomic nucleus; (2) the electromagnetic force that binds electrons to the nucleus and is responsible for chemical interactions; (3) the weak force that is involved in radioactive decay; and (4) the gravitational force that attracts all masses. It provides a table matching examples of interactions between different particles and molecules with the corresponding fundamental force.

1. FindingForces
NOVA Activity The Elegant Universe
There are four fundamental forces that govern the
interactions of matter. Read the descriptions of these
on your Forces of Nature activity sheet (in “The Four
Fundamental Forces”section) and assign the correct
letter to the number on this page that represents the
area of matter governed by that force.
1
2
3
4
MOLECULES
CELLS
WATER
MOLECULE
hydrogen
atom
up
quark
up
quark
down
quark
hydrogen
atom
protons
and
neutrons
electron
anti-
neutrino
electron
OXYGEN
ATOM PROTON
PROTON
W-
W-
force
carrier
particle
U
U D
U
U D
up
quark
down
quark
down
quark
NEUTRON
NEUTRON
D
U DD
U D
oxygen
atom
e-
␯