Earth and Space!!!! Flashcards
What is orbital speed? And what is the equation for it?
☆When planets move around the sun, or when a moon moves around a planet, they orbit in circular motion.
☆In one orbit, a planet travels a distance equal to the circumference of a circle.
☆ orbital speed = 2πr
t
r = average radius of orbit (m)
t = orbital time period (t)
What is acceleration? And what is its equation?
☆Acceleration is the rate of change in velocity (change in speed)
☆Acceleration (m/s2) = final velocity (m/s) - initial velocity (m/s) divided by time (s)
☆Acceleration is the change of velocity over time, it is a vector quantity. The direction of velocity is changing therefore an object can accelerate without its speed changing.
Newton’s second law -
☆F = ma
resultant force (N) = mass (kg) x acceleration (m/s2)
☆The equation shows that the acceleration of an object is:
*Proportional to the resultant force of an object
*Inversely proportional to the mass of an object
Basically, it is saying that the acceleration of an object increases if the resultant force on it increases, and decreases if the mass of the object increases.
What is mass?
☆Mass is the measure of matter (atoms) an object is made of
☆It is measured using kg
What is weight?
☆The weight of an object is the force on it caused by gravity due to the planet. Weight and gravitational field strength are proportional. For a given mass, the greater the gravitational field strength of the plant, the greater the weight.
What is the equation for weight?
W = mg
Weight (N) = mass (kg) x gravitational field strength (N/kg)
Can your mass and weight change?
☆Your weight can change depending on the gravitational field strength of your location, for example, you would weigh less on the moon than on earth as it has a weaker gfs.
☆Your mass would stay the same no matter where you are as it depends on the number of atoms you are made of and that would not change no matter where you are.
What are the different parts of the solar system?
☆The sun - The earth’s star, is the largest object in the solar system. The sun’s huge gravitational strength keeps many objects in its orbit.
☆Eight planets - Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. For a planet to form, its own gravity must be strong enough to make it round or spherical in shape. Its gravitational field strength must be strong enough to pull in all nearby objects.
☆Natural satellites - The moon is an example of a natural satellite, they orbit planets.
☆Artificial satellites - They are man made and can orbit any object in space.
☆Dwarf planets - Gravitational field strength of dwarf planets is not strong enough to have pulled in all nearby objects so there may be other objects in its orbit around the sun.
☆Asteroids - Made of metal and rocky material. Large amounts of asteroids orbiting the sun in the asteroid belt between mars and jupiter.
☆Comets - Are made of dust and ice. As a comet approaches the sun, it begins to turn from liquid to gas (vapour). It then produces a comet’s tail.
What happens in the nebula stage?
☆Stars begin as a cloud of gas and dust brought together by gravity. The gravity is what causes the star to become more hot and dense.
What happens in the protostar stage?
The temperature and pressure become high enough the hydrogen nuclei undergo fusion to become helium nuclei. The energy released from this reaction is what keeps the core of the star hot.
What happens in the main sequence stage?
☆The outward pressure caused by the fusion reaction becomes balanced with the gravitational force caused by the mass of the star. Stars usually leave this stage when hydrogen begins to run out. The stars stable stage.
What happens in the red giant stage for low mass stars?
☆If the star is the same size as the sun or less, it becomes unstable and expands.
What happens in the planetary nebula for low mass stars?
☆The star ejects its outer layer
What happens in the white (black) dwarf stage for low mass stars?
☆White dwarf is the small hot core of the star which then cools down to form a black dwarf.
What happens in the red super giant for high mass stars?
☆If the star is much bigger than the sun, they expand and become more hot as fusion occurs in heavier elements creating elements up to iron.
