Notes, abstracts, papers, exams and problems of Physics

Kinetic Energy and Potential Energy

Kinetic Energy (KE) Calculation:

A body with a mass of 50kg has a velocity of 20 m/s.

KE = (1/2) * M * V²

KE = (1/2) * 50kg * (20 m/s)²

KE = (1/2) * 50 * 400

KE = 10000 Joules

Total Energy Calculation:

A body with a mass of 5kg is at a height of 10m and moving at a speed of 20 m/s. Calculate its total energy.

Mass (M) = 5kg

Height (H) = 10m

Velocity (V) = 20 m/s

Potential Energy (PE) = M * g * H = 5kg * 9.8 m/s² * 10m = 490 Joules

Kinetic Energy (KE) = (1/2) * M * V² = (1/2) * 5kg * (20 m/s)² = 1000 Joules

Total Energy = KE + PE = 1000 Joules + 490 Joules = 1490 Joules

Heat Transfer and Temperature Conversion

Kelvin to Celsius Conversion:

How to convert 300 Kelvin to Celsius, as applicable to converting 100 Celsius to Kelvin.... Continue reading "Kinetic Energy, Heat Transfer, and Algebraic Equations" »

Kinematics Formulas

Position Vector

r = xi + yj

• x = r cos
• y = r sin
• r = √(x² + y²)
• tan θ = y / x

Displacement

Δr = r - r_initial

Speed, Average Speed, Instantaneous Speed

• Average Speed: v_av = Δr / Δt
• Instantaneous Speed: v = dr / dt

Average Acceleration, Instantaneous Acceleration

• Average Acceleration: a_av = Δv / Δt
• Instantaneous Acceleration: a = dv / dt

Uniform Rectilinear Motion (MRU)

• v = Δx / Δt
• v_mean = (v₀ + v) / 2
• v = v₀ + at
• x = x₀ + vt
• x = x₀ + v₀t + (1/2)at²
• v² - v₀² = 2aΔx
• v² = v₀² ± 2as

Free Fall

• Velocity: v = gt
• Position (height fallen): y = (1/2)gt²
• Velocity (upward): v = -gt
• Position (height): y = y₀ - (1/2)gt²

Upward Vertical Launch

• Velocity: v = v₀ - gt
• Position (height): y = y₀ + v₀t - (1/2)gt²
• Time to reach maximum height: t = v₀ / g
• Maximum

Magnetic Hysteresis in Ferromagnetic Materials

When a magnetic material is subjected to a changing magnetic field intensity (H), the magnetic induction (B) lags behind. This phenomenon is known as magnetic hysteresis. (See Figure 1). When a ferromagnetic substance is subjected to a cyclical (alternating positive and negative) magnetic field intensity, it traces a hysteresis loop.

Key points on the hysteresis curve (See Figure 1):

• O-B: Magnetization curve.
• O-R: Residual magnetization.
• O-D: Coercive force.

When applying an alternating magnetization intensity (+ and -) to a ferromagnetic substance, the resulting hysteresis loop is shown in the image. The magnetic induction (B) lags behind the magnetic field intensity (H). At point B, even when H = 0,... Continue reading "Magnetic Hysteresis & Autoinduction Explained" »

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" »

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