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

What is Force?

Force is a push or pull that can deform an object or change its state of rest or motion.

Types of Forces

• Contact
• Non-contact
• Instantaneous
• Constant

Formula of Force

F = m • a

Difference Between Force and Weight

Weight is a force. Everything on Earth is pulled down towards the ground by gravity. The weight of an object is how hard gravity pulls down on it.

Larger objects get pulled more strongly, so they weigh more than smaller objects. When scientists want to talk about how much stuff is inside something, they talk about mass.

Causes of Force

Forces arise when two or more bodies come into contact. For example, when there is a crash or when you push a door.

Bodies, even if they are not in contact, exert a force on others. For example, the... Continue reading "Understanding Force, Motion, and Newton's Laws" »

The Gothic Novel

Origins and Conventions

Gothic literature, a movement that focused on ruin, decay, death, terror, and chaos, and privileged irrationality and passion over rationality and reason, grew in response to the historical, sociological, psychological, and political contexts of the late eighteenth and early nineteenth centuries. Although Horace Walpole is credited with producing the first Gothic novel, The Castle of Otranto, in 1764, his work was built on a foundation of several elements. Walpole’s novel was wildly popular, and his novel introduced most of the stock conventions of the genre:

• An intricate plot
• Stock characters
• Subterranean labyrinths
• Ruined castles
• Supernatural occurrences

While it may be comparatively easy to date the beginning... Continue reading "The Gothic Novel: Exploring the Dark Side of Human Nature" »

Earth, Moon, and Space: Key Concepts

1. Day and night are caused by:

   d. Earth's rotation on its axis.

2. Earth's rotation takes about:

   c. 24 hours.

3. One complete revolution of Earth around the sun takes about:

   c. one year.

4. Earth has seasons because:

   c. Earth's axis is tilted as it moves around the sun.

5. When the north end of Earth's axis is tilted toward the sun, North America will experience:

   d. more direct rays and longer days.

6. In the Southern Hemisphere, the summer solstice occurs when the sun is directly overhead at:

   b. 23.5° south latitude.

7. An equinox occurs when:

   a. neither end of Earth's axis is tilted toward nor away from the sun.

8. Because the moon rotates once for each revolution around Earth,

   c. you never see the far side of the moon.

9. The phase of the moon

Extrasolar Planets

An extrasolar planet is a planet orbiting a star other than our Sun. There are two general ways of learning about a distant object: directly, which means by obtaining images or spectra of the object, and indirectly, which means by inferring the object’s existence or properties without actually seeing it. There are two major indirect approaches to finding and studying extrasolar planets:

1. Observing the motion of a star to detect the subtle gravitational tugs
2. Observing changes to a star’s brightness that occur when one of its planets passes in front of the star as viewed from Earth.

Planets exert gravitational tugs on their star, causing the star to orbit around the system center of mass. Gravitational tugs: we can detect a... Continue reading "Discovering Extrasolar Planets: Methods and Significance" »

Introduction

Shock Waves: Formation and Mach Cone Angle

If the speed of a source relative to the medium exceeds the speed of sound in the medium, the Doppler equation no longer applies. In such a case, shock waves result. The half-angle of the Mach cone is given by:

Temperature Measurement and Thermometers

Temperature is an SI base quantity related to our sense of hot and cold. It is measured with a thermometer, which contains a working substance with a measurable property, such as length or pressure, that changes in a regular way as the substance becomes hotter or colder.

Zeroth Law of Thermodynamics: Thermal Equilibrium

When a thermometer and some other object are placed in contact with each other, they eventually reach thermal equilibrium. The reading of... Continue reading "Fundamental Concepts in Thermodynamics and Gas Behavior" »

Write your text here!Bernoulli's theorem, in fluid dynamics, relation among the pressure, velocity, and elevation in a moving fluid (liquid or gas), the compressibility and viscosity (internal friction) of which are negligible and the flow of which is steady, or laminar.

Photons and Electrons in the Double Slit Experiment

Evidence for Wave-Particle Duality

• A single electron or photon leaves the source with particle-like discreteness and creates a single discrete spot on the screen.
• The interference pattern, which occurs over time, is a wave property.

Diffraction Pattern and Heisenberg’s Uncertainty Principle

• We cannot measure the exact position of each electron or its exact momentum as it approaches the slit; there is uncertainty in both position and momentum.
• The uncertainty in each electron’s y-position is reduced to the width of the slit (since we are certain it passes through the slit). This increases its uncertainty in the momentum of the y-direction.
• The uncertainty in the momentum in the y-direction means