Forces, Earth's History, Evolution and Astronomy Flashcards

Flashcards based on lecture notes about Forces and Earth's History

What is a Force?

A push or a pull on an object.

What are the two measurements taken when measuring force?

Magnitude (strength) and direction.

What is a vector?

An arrow describing a force's direction and magnitude.

How to calculate Force

Mass x Acceleration

How to calculate Acceleration

Force / Mass

How to calculate Mass

Force / Acceleration

What unit is used to measure force?

Newton (N)

What is inertia?

Mass resisting a change in motion.

Adding Forces

Forces in the same direction make a bigger force.

Subtracting Forces

Forces in opposite directions subtract from each other.

Forces in Different Directions

Forces in opposite directions subtract from each other.

Net Force

The overall force on an object, once all the individual forces are added up.

Balanced Forces

When net forces are equal, there is no change in motion.

Unbalanced Force

Forces that do not add up to zero, resulting in motion.

Acceleration

A change in velocity when an object speeds up, slows down, or changes direction.

What unit is used to measure Acceleration?

m/s² (meters per second squared)

What unit is used to measure Mass?

Kilograms/grams (kg/g)

Is mass the same as weight?

No, they are not the same thing.

Mass

Atoms and molecules in an object (matter).

Weight

A force of how hard gravity pulls on something; measured in Newtons (N).

How to calculate Weight

Mass x Gravity

How to calculate Gravity

Weight / Mass

Earth's Gravity

9.8m/s^2

Newton's First Law of Motion

The Law of Inertia: An object's tendency to resist a change in motion.

Newton's Second Law of Motion

The Law of Acceleration: The force of an object is equal to its mass multiplied by its acceleration.

Newton's Third Law of Motion

The Law of Action-Reaction: For every action, there is an equal and opposite reaction.

Friction

A force that resists motion between two surfaces.

Static Friction

Friction between two surfaces that are not moving.

Sliding Friction

Friction that resists the motion of a sliding object.

Rolling Friction

Friction that resists the motion of an object rolling across a surface.

Viscous Friction

Friction that resists the motion of an object moving through a liquid.

Air Friction

Friction that resists the motion of an object moving through air.

Geologic Time Scale

System used to measure and describe the history of Earth.

What are eons?

Large time units dividing Earth's "life."

Precambrian Supereon

Hadean, Archean, and Proterozoic Eons; believed no multicellular life existed.

Eras

Smaller units of time within eons, based on events.

Phanerozoic Eon

Eon divided into Paleozoic, Mesozoic, and Cenozoic Eras, defined by life forms and extinctions.

Periods

Subdivisions of eras.

First life forms on Earth

Small, simple, anaerobic microbes.

Multicellular life appeared

550 mya

First vertebrates appeared

486 million years ago and were jawless fish

The first reptiles appeared

300 mya

Earliest dinosaurs appeared

225 million years ago, during the Triassic Period

First primates appeared

60 million years ago

First humans appeared

2 million years ago

Extinction

Complete loss or death of a species.

Mass Extinction

Event when a large number of species die out simultaneously.

Ordovician-Silurian Mass Extinction

Occurred 443 mya, killed 85% of ocean species.

Late Devonian Mass Extinction

Occurred 359 mya, killed 75% of all species.

Permian Mass Extinction

Occurred 248 mya, killed 96% of species; "The Great Dying".

Triassic-Jurassic Mass Extinction

Occurred 200 mya, killed 50% of species.

Cretaceous-Tertiary Mass Extinction

Occurred 65 mya, killed dinosaurs.

Fossils

Preserved remains of a once living organism.

Where are fossils often found?

Sedimentary rocks

Mold Fossil

impression of a once-living organism.

Cast Fossil

Filled-in mold fossil.

Trace Fossil

Fossil of biological activity (e.g., footprint).

True Fossil

Actual organism or part of the organism is preserved.

Petrified Fossil

Organic matter replaced by minerals and turned into stone.

Index Fossils

Fossils used to date unknown fossils; widely distributed and limited in time span.

Relative Dating

Determining the relative age of rock layers and fossils.

Law of Superposition

Sedimentary rock layers are laid down on top of each other, with the bottom layer being the oldest.

Principle of Original Horizontality

Sediment is deposited horizontally.

Cross-Cutting Relationships

A fault or fracture is younger than the rock layer it cuts through.

Intrusive Relationships

Igneous intrusion is younger than the rock layers it cuts through.

Absolute Dating

Determining the age of rocks and fossils using radioactive dating.

Carbon-14

Radioactive carbon used in dating fossils.

Half-life

Time it takes for half a radioactive sample to decay.

How long is a half-life?

5730 years

Evolution

The change of traits in a species over successive generations (time).

Competition

The driving force for evolution.

Five Resources Individuals Compete For

Food, shelter, space, water, and mates.

Common Ancestor

An organism from which different species of organisms evolved.

Rapid Evolution

Occurs when a change happens in the environment that leads to a species evolving quickly.

Natural Selection

Individuals within a species that are better suited for the environment are more likely to survive. They reproduce and pass their characteristics onto offspring

Variation

The differences between individuals of a species

Recombination

During sexual reproduction, DNA from two different parents is divided and recombined to form a unique combination of DNA in an offspring.

Mutation

A change in the DNA code.

Artificial Selection

Humans intentionally select plants or animals with desirable traits and then purposely breed those organisms to produce more organisms with favorable traits.

Ancient Organism Remains - Evidence For Evolution

The fossils of some ancient organisms suggest organisms today are similar to organisms that existed many years ago

Genetic Similarities - Evidence For Evolution

Scientists compare the DNA of different species. The more similar DNA, the more closely related the species

Anatomical Similarities - Evidence For Evolution

Many organisms have anatomical similarities or similar body plans

Comparative Anatomy

Scientists often compare the structure, or anatomy, of different species.

Homologous Structures

Structures that look the same but have different functions

Analogous Structures

Different arrangement of structures possessed by different species that are adapted to perform the same function

Vestigial Structures

Structures within an organism that are functionless.

Embryology Similarities - Evidence For Evolution

Embryos of very different animals look surprisingly similar.

Fossils - Evidence For Evolution

Older fossils look very different from very recent fossils

Big Bang Theory

The most widely accepted theory to explain the origin of the universe (not the only theory)

Light-Years

A light-year is the distance light travels in one year (about 9.5 trillion kilometers)

Galaxy

A huge system of millions or billions of stars, together with gas and dust, held together by gravity

Milky Way Galaxy

The name of the spiral shaped galaxy in which we live in

For centuries, people assumed __ was at the center of the solar system.

Earth

Geocentric

Earth-centered

Heliocentric

Sun is the center of the solar system with the planets orbiting the Sun and the stars remaining stationary (not moving)

Gravity

The force that pulls all objects with mass toward one another

Planetary System

There are many planetary systems like ours in the universe, with planets orbiting a host star.

Inner Planets

Mercury, Venus, Earth, Mars

What planet has the fastest orbit?

Mercury

What planet has retrograde rotation?

Venus