Physics 101 Flashcards
What is the unit of energy?
Joules (J)
What are the ways of transferring energy?
Thermal, electrical, light, and sound
What are the ways of storing energy?
Kinetic, chemical, potential, nuclear
What is kinetic energy?
The that an object stores because it is moving
What is potential energy?
The stored energy an object has because of its position or shape
What are the two types of potential energy?
Gravitational potential energy and elastic potential energy
What is the conservation of energy?
Energy cannot be created or destroyed. It can only be transferred from one form to another
What is efficiency?
The percentage of the energy that a machine transfers as useful energy
How do you calculate efficiency?
efficiency = useful energy transferred / total energy transferred x 100
Where does Earth get most of its energy from?
The sun
What is energy?
The ability to do work
How do you increase the internal energy of an object?
By heating the object
What is specific heat capacity?
The amount of thermal energy required to raise 1 kg of a substance by 1 C
What is conduction?
The travel of thermal energy through solids
What is a thermal conductor?
A solid which allows heat to travel through them easily
What is an insulator?
A material that doesn’t let heat flow them easily
Explain how layers of clothes keeps a human warm:
The clothes act as an insulator and reduce the rate at which heat is lost to surroundings. If you wear multiple layers of clothing the air is trapped between the clothes and keeps you warm because trapped air is an excellent insulator
Explain thermal conduction:
When a solid is heated it’s particles move faster. When the particles vibrate they collide with the neighboring particles. This causes the neighboring particles to move faster as well. The thermal energy is passed through the solid like a chain.
What is convection?
The transfer of thermal energy in liquids and gases
Explain convection current:
When air is heated it expands. The mass of air occupies a larger volume, making it less dense than the colder air around it
Why is land heated faster by the sun than the sea?
Because the heat capacity of water is larger than the heat capacity of the land
What is a thermal?
A rising air current due to local heating of air
What is radiation?
The transfer of thermal energy in electromagnetic waves
Why are houses in hot countries often painted white?
Because white surfaces are poor absorbers of radiation
What is evaporation?
When a liquid turns into a gas
Explain how a person feels cold when they’re wet on a windy day:
When your body/clothes are wet, your body heats the water. The thermal energy from your body is transferred to the water, making the water molecules move faster. Since the thermal energy is leaving your body to the surroundings, you feel cold
How does heat escape from a hot drink through conduction?
Through the cup wall
How does heat escape a hot liquid to through evaporation?
From the surface of the liquid
How does heat escape from a hot liquid through convection?
Warm air rises after being heated by the hot drink
How does heat escape from a hot liquid through radiation?
From the surface of the cup
What is the Big Bang theory?
The theory that all matter started as a tiny dense hot mass and I gradually expanding
How does a red shift work?
When an object is moving away from us it’s light is distorted, giving a redder color
Define galaxy:
Millions of starts grouped together
Explain nuclear fusion:
The sun doesn’t burn, inside the sun there are hydrogen atoms which join together to produce helium atoms
What is a white dwarf?
When a small sun collapses
What is a black hole and explain it:
A black hole is when a big sun collapses and creates a gravitational pull.
What is a planet?
A large object orbiting a star
How were the planets and the sun formed?
From a swirling cloud of dust and gas
How many planets are in the solar system?
8
How are planets held in their orbit?
By the Sun’s gravity
How are planets seen?
The sun is a luminous object and it’s light is very strong. The planets reflect off the light of the Sun and are then seen
What is the shape of the planet’s orbits?
Elliptical (oval)
Describe Mercury:
Closest planet to the Sun, has the shortest year due to it’s space with the Sun
Describe Venus:
Hottest planet, due to carbon dioxide in its atmosphere causing a green house effect. Clouds of sulphuric acid
Describe Earth:
Only lamer which can support life, because the temperature is not too hot or cold, liquid water on there surface and clouds of water vapor around it
Describe Mars:
Rocky mountainous planet that looks red. Thin atmosphere made up of carbon dioxide
Describe Jupiter:
Largest planet, mainly made up of hydrogen and helium. Has a ring around it made up of rock and ice crystals. Largest moon is Ganymede
Describe Saturn:
Mainly made up of hydrogen and helium, has rings around it made up of rocks and ice crystals. Least dense planet
Describe Uranus:
Has many rings made from rock and ice. Has an atmosphere of hydrogen, helium and methane
Describe Neptune:
Has rings, atmosphere made up of blue methane. Has the fiercest winds.
Name all the planets in the solar system:
Mercury - Venus - Earth - Mars - Jupiter - Saturn - Uranus - Neptune
How is a body considered as a planet?
To be big enough and spherical, and to have “cleared its orbit”
What is a dwarf plant?
A planet that orbits the Sun and is spherical, but not big enough to clear its orbit
What is an asteroid?
A small rocky body mostly orbiting between Mars and Jupiter
What is a meteoroid?
A small piece of asteroids or comets.
What is a meteor shower?
Lots of meteors seen together over a few hours or a day
What is a meteor?
When a meteoroid enters Earth’s atmosphere
What is a meteorite?
When a meteoroid enters Earth’s atmosphere and survives the the atmosphere and hits the Earth
What is a comet?
A lump of ice and dust orbiting the sun.
How long does it take for the Earth to spin around it’s axis once?
24 hours
What degree is the Earth’s axis tilted to?
23.5 degrees
How many days does it take the Earth to orbit the Sun?
365 days and 6 hours
What is a leap day?
An extra day at the end of February every 4th year
When is leap day?
February 29
What is leap year?
A year with 366 days
How many days does it take for the moon to go around the Earth?
29 days and 12 hours or 29.5
Is the moon an artificial satellite?
No. The Moon is a natural satellite
What is a natural satellite?
Something orbiting a planet that is not man-made
Explain how we can see the moon:
The Sun shines it light and the moon reflects it
Explain a new moon:
When the moon is in between the Sun and the Earth and the lit up side is not seen by the Earth
What are the phases of the Moon?
New moon, crescent moon, half moon, and full moon
What is a lunar eclipse?
An eclipse of the moon when the moon goes into the shadows of the Earth
What is a solar eclipse?
When the Moon goes in between the Sun and the Earth and blocks the Sun’s rays
Does the Moon spin on its axis?
No. The same side of the Moon always faces the Earth
What is mass?
A measure of the amount of matter something is made of
What is mass measured in?
Grams (g) and Kilograms (Kg)
What is weight?
The amount of force which gravity pulls on an object
What is weight measured in?
Newtons (N)
What is gravity?
The affect of gravitational attraction between masses
How many newtons is 1 kg?
10 Newtons
How many kg is 2,400 Newtons?
240 kg
What happens to gravity as you get further away from Earth?
The influence of gravity decreases
How do satellites orbit the Earth?
The Earth’s gravitational force keeps satellites from flying off in space
What is an artificial satellite?
A man-made object placed in an orbit around the Earth
How long does it take for an artificial satellite to orbit Earth?
It can be controlled by choosing the height of its orbit
What is a geostationary orbit?
An orbital path above the Equator in which it takes 24 hours to complete one orbit. The object stays in the same place and position
How long is the average radius of the Moon’s orbit?
384,000 km
Who was Ptolemy?
An Egyptian astronomer who lived in Alexandria
How did the Greeks discover the Earth is round?
They measured the angle of the Sun at two places a known distance apart and worked out the circumference of the Earth
What did Nicole Copernicus discover?
The Sun is the center of our solar system and all the planets are orbiting it
What did Tycho Brahe make?
Accurate observations of the planets
What did Galileo Galilei do?
He was the first person to use the telescope scientifically
