Notes, summaries, assignments, exams, and problems for Physics

Energy

Energy is the capacity of bodies to produce transformations in themselves or other bodies.

Energy Sources

Energy sources are natural resources from which humans can obtain usable energy.

Types of Energy Sources

• Non-renewable: Found in limited quantities and are depleted with use.
• Renewable: Considered inexhaustible as they are continuously renewed.

Energy Principles

• Conservation of Energy: The total energy in the universe remains constant in any process.
• Degradation Principle: With each transformation, energy loses quality and produces new transformations.

Work and Power

Work (W) is done when a constant force (F) is applied to a body, causing a displacement (d) in the same direction as the force: W = F * d.

Power is the rate at which work is done.... Continue reading "Energy, Waves, Sound, Light, and Electricity: Physics Fundamentals" »

Law of Gravitation

Every object in the universe that has mass exerts a gravitational attraction on other objects with mass, regardless of the distance between them. According to this law, more massive objects exert a greater force of attraction. In parallel, the closer objects are, the greater the force, following an inverse square law.

Considering two masses whose size is small compared with the distance that separates them, we can summarize this in an equation or law that states that the force exerted by a given object with mass m1 on one with mass m2 is directly proportional to the product of the masses and inversely proportional to the square of the distance between them.

A force is central where the position vector r is parallel to the force... Continue reading "Fundamental Physics Concepts Explained" »

44. (a) The Young’s modulus is given by

(b) Since the linear range of the curve extends to about 2.9 × 10⁸ N/m², this is approximately the yield strength for the material.

46. Since the force is (stress × area) and the displacement is (strain × length), we can write the work integral (eq. 7-32) as

  W =

  = A (differential strain)L  = AL (differential strain)

which means the work is  (wire-area) × (wire-length) × (graph-area-under-curve).  Since the area of a triangle (see the graph in the problem statement) is  (base)(height)  then we determine the work done to be

            W = (2.00 x 10^-6 m²)(0.800 m)(1.0 × 10^-3)(7.0 × 10⁷ N/m²) = 0.0560 J .

48. 46. Since the force is (stress × area) and the displacement is (strain... Continue reading "Young's Modulus and Material Strength Calculations" »

Abbe Operation

Abbe Operation is based on the determination of the critical angle. The technique is to calibrate the device, usually with distilled water at 20ºC, by matching the shade formed by the prism surface illuminated by a brand (not recorded) in the center of the telescope. Perform the same operation with the test sample to make the correct reading of the refractive index in the eyepiece of the telescope. Since the refractive index varies with temperature, it is important to perform the measurement with the apparatus thermostatted at 20°C or at least know the temperature at which to make the determination.

Understanding Light Polarization

• Natural Light: It is a vibration in all directions perpendicular to the beam.
• Polarized Light: It