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Kinetics of Particles
Published in M Rashad Islam, A K M Monayem H Mazumder, Mahbub Ahmed, Engineering Dynamics, 2022
M Rashad Islam, A K M Monayem H Mazumder, Mahbub Ahmed
Although we are familiar with different kinds of forces in nature and these forces have different names, all forces are not fundamental. The fundamental or natural forces are those that are not derived from other forces; rather, these other forces are derived from the fundamental forces. In nature there are four fundamental forces. Other forces can be explained by one or more of the fundamental forces. These fundamental forces are:Gravitational Force – the attraction force between any two particles or objects, including the Earth.Electromagnetic Force – the force between two charged particles and between two magnetic materials.Strong Nuclear Force – the strong attraction force that keeps the nucleus stable in an atom.Weak Nuclear Force – the weak force that emits neutrino and β-particles from radioactive nuclei such as uranium, thorium, etc.
Green Nanomaterials: Synthesis, Properties and Spectroscopic Applications
Published in Kaushik Pal, Nanomaterials for Spectroscopic Applications, 2021
Muammer Din Arit, Md Asadur Rahman, Md Mahmudul Hague Milu, Abu Bakar Siddik, Md Enamul Hogue
On the other hand, the electromagnetic force depends on the charge and distance of two particles, and this force is not affected by mass. It acts based on the charge and magnetic properties of nanoscale materials. When the charge or magnetization is increased between two particles, this electromagnetic force also increases. Besides, this force decreases when the distance between the particles increases. Nanoscale materials have negligible mass so there are no effects of gravitational force on nanoscale materials rather nanoscale materials depend on the electromagnetic force. There are two other forces—strong and weak nuclear forces. These forces act on the particles which are at a short distance and composed of a nucleus and therefore, this force also becomes negligible in nanomaterials, as they are considerably bigger than atoms. Therefore, gravitational and other nuclear forces turn to be negligible meanwhile, in nanoscale materials electromagnetic forces become dominant.
Images from Radioactivity: Radionuclide Scans, SPECT, and PET
Published in Suzanne Amador Kane, Boris A. Gelman, Introduction to Physics in Modern Medicine, 2020
Suzanne Amador Kane, Boris A. Gelman
The reason that protons and neutrons stick together inside the nucleus in the first place has to do with the strong nuclear attractive force by which all nucleons interact with each other. This strong nuclear force only operates at extremely short distances, unlike the electrical force between two charged particles, which is present at all separations. That is, two charged particles always exert an electrical force on each other no matter how far apart they are, but two nucleons only one nucleon's width apart exert essentially no force on each other. The short-ranged strong nuclear force creates a generally attractive interaction between the nucleons within a nucleus. The strength of nuclear interaction between a pair of neutrons, a pair of protons, and a proton–neutron pair is about the same. Nuclear forces are felt or exerted only by nucleons, never by electrons. In addition to the nuclear forces, the protons in a nucleus also experience electrical forces that occur, because many particles of like charge (the protons) are confined to a small volume. As a result, the protons repel one another strongly, so they could not be confined to the nucleus without the balancing effect of the attractive nuclear forces between all nucleons. The field of nuclear physics has been developed to understand how these two competing effects (the repulsion between protons versus the attraction between all nucleons) cause the observed organization of nuclei in nature. We will look at a few consequences of this competition shortly.
Effect of 14.7-MeV Protons and 3.6-MeV Alpha Particles on Fusion Structural Materials
Published in Fusion Science and Technology, 2020
S. I. Radwan, S. Abdel Samad, H. El-Khabeary
Fusion power is a power generation in which energy is generated by using nuclear fusion reactions to produce heat for electricity generation through a device named the thermonuclear reactor.1 Fusion reactions occur when two or more light atomic nuclei come close enough at a distance of 10−15 m to form a heavier atomic nucleus, then the nuclear force pulling them together exceeds the electrostatic force pushing them apart, fusing them into heavier nuclei.2 The strong force becomes effective at this distance and the two nuclei unite into one nucleus. Since the atomic nuclei have positive charges, they must overcome the Coulomb potential in order to approach each other within 10−15 m. The light nuclei must be moving at high speed in their collision. Thus, the nuclei are either accelerated or heated to a high temperature. Fusion processes require fuel and a highly confined environment with a high temperature and pressure to create a plasma in which fusion can occur. Fusion reactors generally use hydrogen isotopes, such as deuterium and tritium, that react more easily and create a confined plasma of millions of degrees using inertial methods (laser)3–6 or magnetic methods (tokamak and similar),7,8 although many other concepts have been attempted. Fusion reactions are of two basic types: (1) those that preserve the number of protons and neutrons and (2) those converted between protons and neutrons. Reactions of the first type are the most important for practical fusion energy production, whereas those of the second type are crucial to the initiation of star burning.