Motion in the Universe Flashcards
What is a universe?
a large collection of billions of galaxies
What is a galaxy?
a large collection of billions of stars
What galaxy is our solar system in?
the Milky Way galaxy
What does a star’s colour relate to?
its surface temperature
What colour star is the coolest and around what temperature is it in Kelvin?
a red star is the coolest at around 3000K
What colour star is the hottest and around what temperature is it in Kelvin?
a blue star is the hottest at around 30 000K
What happens to a star when it becomes a red giant?
it becomes redder as it expands and cools
What happens to a star when it becomes a white dwarf?
it becomes whiter as it contracts and heats up
What is a known fact about astronomical objects?
astronomical objects cool as they expand and heat up as they contract
Why does gravitational field strength (g) vary on different planets?
an object’s gravitational field strength depends on its MASS
Why does the Moon have a weaker gravitational field than Earth?
the Moon has less MASS than the earth, so its gravitational field strength is much weaker (approx a 1/6th of the Earth’s)
How does a large radius on a planet effect its gravitational field strength?
a planet with a larger radius will have a weaker gravitational strength at its surface because surface is further away from the centre of the planet
What is weight defined as?
the force acting on an object due to gravitational attraction
What is the force of weight responsible for?
-objects staying firmly on the ground
-objects always falling to the ground
-satellites being kept in orbit
What is the gravitational field strength on Earth?
approximately 10N/kg
What is the descending order of the gravitational field strength on plants in our solar system?
SUN
JUPITER
SATURN
URANUS
EARTH
MARS
MOON
Why would a human not be able to stand up on Jupiter?
Jupiter has a greater gravitational field strength so the human’s weight will become larger
Why does the Moon not crash into the Earth and the plants don’t crash into the Sun?
the Moon does not crash into the Earth, and the planets do not crash into the Sun because they are moving
What does the gravitational force that keeps planets moving in curved paths create?
orbits
What four things does gravitational force (gravity) cause?
-causes moons to orbit planets
-causes the planets to orbit the Sun
-causes artificial satellites to orbit the Earth
-causes comets to orbit the Sun
What are some similarities in the way different planets orbit the Sun?
-their orbits are all slightly elliptical (stretched circles) with the Sun at one focus
-they all orbit in the same plane
-they all travel in the same direction around the Sun
What are some differences in the way different planets orbit the Sun?
-they orbit at different distances from the Sun (different orbital radius)
-they orbit at different speeds
-they all take different amounts of time to orbit the Sun
How does a planets distance from the Sun effect the time it takes to orbit?
the further away a planet is from the Sun, the slower it travels and therefore the longer it takes to orbit
What does a planet orbit?
the Sun
