They are man-made satellites that orbit the Earth such as those used for satellite TV and GPS systems.
3 of 25
What allows planets and satellites to maintain these circular orbits?
The force of gravity.
4 of 25
HT What must happen for an object to travel in a circular path?
There must be a force that acts towards the centre of the circle.
5 of 25
HT What acts towards the centre for planets and satellites?
The force of gravity.
6 of 25
HT What does this unbalanced force result in?
An acceleration towards the centre.
7 of 25
HT What happens with veloctiy and acceleration in relation to an object undergoing circular motion?
Acceleration does not cause the object to change speed, but it does cause the object to change direction. The velocity changes but the speed remains the same, the instantaneous velocity is perpendicular to the centripal force.
8 of 25
HT What creates a centripal force?
The force of gravity pulls the object (whilst it orbits) in a curved path, this creates a centripal force.
9 of 25
HT What may cause an orbit to change or fail?
Changing its speed.
10 of 25
HT How must they stay in a stable orbit?
At a particular distance from the large body, the smaller body must move at a particular speed.
11 of 25
HT What must happen if the speed changes?
The radius of the orbit must also change.
12 of 25
HT In a stable orbit what does the radius correlate with?
The greater the radius, the lower the speed.
13 of 25
When a source of waves is moving, what are the waves it produces?
The waves are squashed together as it moves towards a detector, reducing the detected wavelength. They are also spread apart as it moves away from a detector, increasing the detected wavelength.
14 of 25
What is this effect called and when is this noticeable?
The doppler effect, it is noticeable with sound waves produced by cars, the pitch appears to change if the car is travelling towards or away from an observer.
15 of 25
What does this same effect also happen with?
Light.
16 of 25
If a source of light is moving away from an observer what happens to the wavelength?
The wavelength becomes longer and in turn, redder.
17 of 25
What happens the faster the source is moving away from an observer?
The greater the observed increase in wavelength, the greater the redshift.
18 of 25
Why is there an observed increase in the wavelength of light from distant galaxies?
The further away the galaxies are, the greater the red-shift.
19 of 25
What does this indicate?
This indicates that the more distant the galaxy, the faster it is moving away from us.
20 of 25
What do red-shift observations indicate?
All the galaxies in the universe are moving away from one another and the universe is expanding.
21 of 25
What theory does this provide support for?
The Big Bang theory.
22 of 25
What does the Big Bang theory propose?
It proposes that the universe began from a very small region that was extremely hot and dense.
23 of 25
From 1988 onwards, what do observations of supernovae suggest?
They suggest that distant galaxies are receding even faster. The rate of the expansion of the universe is increasing.
24 of 25
How do scientists currently suggest the universe is increasing?
They suggest that it is linked to dark matter and dark energy, but little is known about these phenomena and many more observations will be needed before a theory is agreed.
25 of 25
Other cards in this set
Card 2
Front
What orbits a planet?
Back
Moons (natural satellites).
Card 3
Front
What are artificial satellites?
Back
Card 4
Front
What allows planets and satellites to maintain these circular orbits?
Back
Card 5
Front
HT What must happen for an object to travel in a circular path?
Comments
No comments have yet been made