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

Understanding Energy Forms

• A circulating car: Kinetic energy.
• A shining light bulb: Thermal and light energy.
• A book on a library shelf: Potential energy.
• A cat chasing a mouse: Kinetic energy.

Kinetic Energy Calculation: Bullet Example

A bullet with a mass of 15 g moving at 50 m/s.

The formula for kinetic energy (Ec) is:

Ec = 1/2 * m * v2

Calculation:

Ec = 1/2 * 0.015 kg * (50 m/s)2 = 18.75 J

Potential Energy Calculation: Crane Example

The formula for gravitational potential energy (Ep) is:

Ep = m * g * h

Calculation for a 350 kg object lifted 7 m (assuming g = 10 m/s²):

Ep = 350 kg * 10 m/s2 * 7 m = 24,500 J

Energy Transformations in Action

Observe the following scenarios and identify who loses/gains energy and the types of energy involved:

• Launching an Arrow

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

Gravitational Acceleration and Field Strength

The strength of the gravitational field depends on the amount of mass $M$ causing the field. Let us define a characteristic of the field that depends only on the mass $M$ and the distance $r$ to the point we consider.

Defining Gravitational Field Strength ($g$)

The gravitational field strength, $g$, at a point in space is the force that would act on a unit mass located at that point. Its unit is Newtons per kilogram ($N/kg$). This term is often used interchangeably with gravitational field intensity.

Calculating the Gravitational Field

To determine the gravitational field created by a point mass $M$, we place a test mass $m$ at a point $P$ in space at a distance $r$ from mass $M$. We calculate the force... Continue reading "Fundamentals of Gravitational Force and Field Calculation" »