p3 1.7 planetary orbits
DESCRIPTION
P3 1.7 Planetary orbits. Learning objectives Be able to explain that; The force of gravity provides the centripetal force that keeps planets and satellites moving in their orbits. To stay at a particular distance, a planet must move at a particular speed around the sun. - PowerPoint PPT PresentationTRANSCRIPT
P3 1.7 Planetary orbits
Learning objectives
Be able to explain that; 1. The force of gravity provides the centripetal force that keeps planets and satellites moving in their orbits.
2. To stay at a particular distance, a planet must move at a particular speed around the sun.
3. The larger the orbit the slower the speed and the longer it takes.
If the Earth’s orbit were more elliptical, how would we be affected?
Time for each orbit
Radius
Earth 1.00 1.00
Mars 1.52 1.88
Jupiter 5.20 11.9
Saturn 9.53 29.5
Important:The orbits on this slide are not shown to scale!
(AU) (years)
0.240.39Mercury
Venus 0.72 0.61
P3 1.7 Planetary orbits
What does this data show?
Speed = dist R time T
P3 1.7 Planetary orbits
To stay at a particular distance, a planet must move at a particular speed around the sun.
Velocity of planet
Force of gravity on planet
sun
Earth R = 1 AU T = 1 Yr
P3 1.7 Planetary orbits
To stay at a particular distance, a planet must move at a particular speed around the sun.
Velocity of planet
Force of gravity on planet
If its speed is too slow, it will spiral into the sun
If its speed is too high, it will move away from the sun
sun
Earth R = 1 AU T = 1 Yr
P3 1.7 Planetary orbits
To stay at a particular distance, a planet must move at a particular speed around the sun.
Velocity of planet
Force of gravity on planet
If its speed is too slow, it will spiral into the sun
If its speed is too high, it will move away from the sun
sun
speed = dist (2πR) time (T)
speed = 2 π1 1
AU/yr
Earth R = 1 AU T = 1 Yr
P3 1.7 Planetary orbits
The larger the orbit the slower the speed and the longer it takes
Velocity of planet
Force of gravity on planet
sun
Saturn R = 9.53 AU T = 29.5 yr
P3 1.7 Planetary orbits
The larger the orbit the slower the speed and the longer it takes
Velocity of planet
Force of gravity on planet
sun
The speed is less because gravity is weaker when further away.
Saturn R = 9.53 AU T = 29.5 yr
P3 1.7 Planetary orbits
Velocity of planet
Force of gravity on planet
sun
Orbit time is longer because the planet has further to go and it is moving slower.
The larger the orbit the slower the speed and the longer it takes
Saturn R = 9.53 AU T = 29.5 yr
P3 1.7 Planetary orbits
Velocity of planet
Force of gravity on planet
sun
Orbit time is longer because the planet has further to go and it is moving slower.
The larger the orbit the slower the speed and the longer it takes
speed = dist time
Saturn R = 9.53 AU T = 29.5 yr
P3 1.7 Planetary orbits
Velocity of planet
Force of gravity on planet
sun
Orbit time is longer because the planet has further to go and it is moving slower.
The larger the orbit the slower the speed and the longer it takes
speed = 2 π 9.59 29.5
speed = dist time
speed = 0.65 π
AU/yr
Saturn R = 9.53 AU T = 29.5 yr
P3 1.7 Planetary orbits
Elliptical orbits:
The squashed circle orbit has two ‘foci’ F1 & F2
Distances OF1 + OF2 = constant
The sun is at one focus of the ellipse
P3 1.7 Planetary orbits
Q
P3 1.7 Planetary orbits
Learning objectives
Be able to explain that; 1. The force of gravity provides the centripetal force that keeps planets and satellites moving in their orbits.
2. To stay at a particular distance, a planet must move at a particular speed around the sun.
3. The larger the orbit the slower the speed and the longer it takes.