Special Relativity, Uncertainty Principle, Radiation, and Interactions
Special Relativity
A fundamental problem in physics in the late nineteenth century was that the laws of electromagnetism varied by changing the reference system, violating the principle of relativity of Galileo, which was the basis of Newton’s mechanics. Thus, observers in relative motion would get different results when studying electromagnetic phenomena. In 1905, Einstein reconciled the two theories (mechanical and electromagnetism) with his Special Theory of Relativity, which is based on the following
Read MoreConcrete: Properties, Types, and Production
Concrete
Material consisting of cement, water, and aggregates. Additives can be added to improve its characteristics. Concrete is a material with good compressive strength and poor tensile strength. The aggregates do not act directly on the setting of concrete; they make up approximately 80% of the mix. Aggregates provide increased strength, durability, abrasion resistance, and tensile strength. They also give more grip to the mix but make it less workable. Fresh concrete has to have plasticity to
Read MorePhysics Problems: Solutions and Explanations
1. Which of the following statements is correct? Functions of the form y = kxn always give a straight line when plotted on logarithmic paper.
2. Note which of the following results is correct, based on the theory of computation error: (0.23)3 = 0.012.
3. In an experiment, a ball of plasticine falls from a height H = 3.00 ± 0.02 m. The gravity is g = 9.81 ± 0.01 ms-2. If errors are given by uncertainties, the velocity of the ball just before impact with the ground is closer to 7.67 ± 0.03 ms-1.
4.
Read MoreUnderstanding Light: From Ancient Theories to Modern Physics
The Nature of Light
The nature of light has always interested humankind. Scientists, philosophers, and thinkers have attempted to answer seemingly simple questions, such as “What is light made of?” since the oldest civilizations. Science, particularly physics, has no simple answers to these questions. For example, to answer that light consists of photons does not respond unless one agrees on the meaning of the word photon. A photon is not an object that belongs to our ordinary experience, like a
Read MoreUnderstanding Light: Theories and Phenomena
Nature of Light
Newton’s Corpuscular Theory
Light has particle nature: light bulbs emit tiny particles that propagate in a straight line in all directions, colliding with our eyes, producing the sensation of light. Corpuscles, other than for color, can pass through transparent media and are reflected by opaque bodies. This hypothesis justifies phenomena such as the rectilinear propagation of light and reflection, but not refraction.
Huygens’ Wave Theory
Huygens proposed that light consists of wave propagation
Read MoreUnderstanding Laboratory Materials and Earth Sciences
Module 2
The Material in the Laboratory
1 – What is porcelain used for? (Fig. 23)
For heating solutions to dryness. Heat until the solvent is completely eliminated.
2 – Basis of Crystallization.
It is the difference in solubilities at different temperatures.
Example: We have 100 g of water at 80 ºC, which can dissolve 60 g of substance. Now, if we have 100 g of water at 15 ºC, it can dissolve 20 g of substance. If we prepared the solution at 80 °C and left it to cool to 15 °C, 60 g – 20