1 Astrophysics Flashcards
What is a galaxy?
A collection billions of stars rotating about a central point
What type of orbit does a comet have?
Very ellipitcal- with the Sun or star at one focal point.
equation for orbital speed?
orbital speed = 2π x radius / time period
v = 2πr / T
What is the unit for time period (T)?
seconds (s)
What is the unit for orbital speed?
metres per second
What type of orbit does a satellite have?
Circular orbit around the Earth
In which position will the comet be travelling the slowest and why?
The comet travels the slowest at A because the gravitational pull is the smallest at A.
Gravitational pull decreases as distance between celestial objects increases.
In which position will the comet be travelling the fastest and why?
The comet travels the fastest at C because the gravitational pull is the largest at C.
Gravitational pull increases as distance between celestial objects decreases.
What is the name of our galaxy?
The Milky Way
What is the universe?
A large collection of billions of galaxies
What is a geostationary orbit?
The satellite is always over the same point of the Earth- it can be used for satellite television.
Time period = 24 hours
Name one natural satellite orbiting the Earth
The Moon
In the image of a planet orbiting the Sun, how would you label the gravitational pull acting on the planet?
An arrow downward pointing towards the Sun
What happens to the orbital speed of an child on a roundabout in a park if the child halves their distance to the centre of the roundabout?
v = 2πr / T
If radius is halved, orbital velocity is halved for the same time period.
Which type of orbit does a planet have?
circular, slightly ellipitcal or very elliptical
Nearly circular, slightly elliptical
How could you calculate the orbital speed of a person standing on the very edge of a roundabout?
- Use a stopwatch to time 5 full rotations and divide this time by 5. This is the time for one revolution or the time period (T)
- Measure the radius (r) of the roundabout with a tape measure.
- Calculate orbital speed = 2πr/T
Which side of the orbital path is the comet accelerating? decelerating?
The comet accelerates from A to D to C since the gravitational pull is in the same direction as its movement. The gravitational pull is speeding it up.
The comet decelerates from C to B to A since the gravitational pull is in the opposite direction to its movement. The gravitational pull is slowing it down.
Which orbital path shows the orbit of a comet?
Blue or red?
- Blue orbital path
- Comets have elliptial orbits with time period of many years
What force keeps the stars together in a galaxy?
Gravitational pull
Which of the following units is gravitational field strength measure in?
A. N/m2
B. N/kg
C. m/s
B. N/kg
