Modern physics recognizes four fundamental types of interaction between particles: the strong force, the weak force, electromagnetism and gravity. Each force acts in a distinct way over distance, and all operate at different energy values.
The strong force is a residual effect of the color force carried by particles called gluons. Protons are made from smaller particles called quarks, which have a quality known as color. Quarks with different colors are held together by gluons, with the side effect that protons adhere to each other despite their mutually-repulsive positive charges.
The strong force is thus strong enough to overcome electromagnetic repulsion over distances equivalent to the diameter of an atomic nucleus. The weak force is about 10^-16 the strength of the strong force and works to change one type of quark into another. It governs the emission of radiation from a decaying atom, and it is responsible for the buildup of heavy atomic nuclei. The weak force is carried by a type of particle called a boson and works over ranges of 0.1 percent of the diameter of a single proton.
Electromagnetism is familiar to most people, if only because it works over potentially infinite range and is carried by photons. Gravity is, by far, the weakest force, but it also works over infinite distance and is always attractive, so its effects compound with mass and proximity. Gravity is the major force shaping large systems, such as galaxies.Learn More
Ice cubes float in water because ice has a lower density than water. This lower density means that ice weighs less than water in its liquid form.Full Answer >
For a rigid body to be in static equilibrium, without total acceleration, two conditions must be met. First, the vector sum of all forces acting on it must be zero (translational equilibrium). Second, the sum off all torques due to any external force on any axis must be zero (rotational equilibrium).Full Answer >
The reaction force of a flying bird is the upward lift by air it experiences when flapping its wings, according to The Physics Classroom. The reaction force by air is in line with Newton’s third law of motion, which states that every action invokes an equal and opposite reaction.Full Answer >
A rake is third-class lever. The pivot point, called a fulcrum, is at one end, while the load is on the other end. The force is in between. Shovels, spears, elbows and knees are other examples of third-class levers.Full Answer >