Fundamentals of Physics and Global Systems

What is a force?

A force is a push, a pull, or a twist, measured in Newtons (N).

What are the similarities and differences between contact and non-contact forces?

Both can cause changes in shape, speed, or direction. Contact forces act when objects touch (e.g., friction, tension), while non-contact forces act at a distance (e.g., gravity, magnetism).

How can you distinguish between balanced and unbalanced forces?

Balanced forces result in no net force, keeping an object at rest or moving at constant speed. Unbalanced forces cause changes in shape, speed, or direction.

What forces act on an object in straight-line motion on a horizontal surface?

Forces include gravity (Fg) pulling down, a reaction force (FR) pushing up, applied forces (FA), and friction (FF) acting in the opposite direction.

What is the difference between distance and displacement?

Distance is a scalar quantity with magnitude only (e.g., 100m). Displacement is a vector quantity with both magnitude and direction (e.g., 100m East).

How are speed, velocity, and acceleration defined?

Speed is distance divided by time (scalar, e.g., 30 m/s). Velocity is displacement divided by time (vector, e.g., 60 km/h North). Acceleration is the change in velocity divided by time (e.g., 10 m/s²).

What does Newton's 1st Law of Motion state?

An object at rest stays at rest, and an object in motion continues in motion with the same speed and direction unless acted upon by an unbalanced external force.

How does Newton's First Law relate to car safety?

In a crash, if a car stops suddenly, passengers continue moving forward due to inertia. Seatbelts and airbags provide the external force needed to stop them safely.

What are the four spheres of Earth?

Atmosphere (gases surrounding Earth), Hydrosphere (all water), Geosphere (solid Earth), and Biosphere (all living organisms).

What is the difference between weather and climate?

Weather refers to atmospheric conditions at a specific time, while climate is the average of weather conditions over a long period.

What factors influence climate?

The surfaces of the Earth, the orientation of the Earth, and the gases in the atmosphere.

What drives ocean and wind currents?

Currents are driven by warmer fluids moving towards cooler regions, creating circular motions due to differences in density.

What is a greenhouse gas?

A greenhouse gas is a gas that traps heat in the atmosphere, warming the Earth's surface (e.g., carbon dioxide, methane).

What causes the greenhouse effect?

Heat from the sun is absorbed and reflected by the Earth's surface. Greenhouse gases trap some of this heat, keeping the Earth warmer.

What are the major contributing factors to the enhanced greenhouse effect?

Burning fossil fuels, deforestation, farming (especially cattle), industrial emissions, and waste decomposition.

What are the predicted consequences of the enhanced greenhouse effect?

Extreme weather, rising sea levels, ocean warming and acidification, loss of habitats, and reduced biodiversity.

What is a light-year?

A light-year is the distance light travels in one year, approximately 9.46 trillion kilometers.

What are galaxies, stars, nebulae, and black holes?

Galaxies are collections of stars and matter; stars are hot gas balls; nebulae are clouds of gas and dust; black holes are regions with gravity so strong that nothing escapes.

How do the life cycles of medium-mass and high-mass stars differ?

Medium-mass stars become red giants and end as white dwarfs; high-mass stars become red supergiants and end in supernovae, forming neutron stars or black holes.

What evidence supports the big-bang theory over the steady-state theory?

Evidence includes the redshift of galaxies, cosmic microwave background radiation, and observable changes in distant galaxies.

How does the raisin-loaf model explain the expanding universe?

As the dough (space) expands, the raisins (galaxies) move farther apart, illustrating how galaxies are moving away from each other as the universe expands.