Newton's law of gravitation Flashcards
What did Kepler show?
used his own and other scientists measurement to show that each planet orbits the sun
he shown that that r3 / T2 weas the same for all planets
this is Kepler’s third law
What did Newton assume?
he realised that the planets were attracted to the sun and this caused the planets to orbit
he assumed the force of gravitation between a planet and the Sun varies inversely with the square of their distance apart
What does Newton’s law of gravitation assume?
force of attraction between two point masses (or particles) (1) proportional to product of masses (1) inversely proportional to square of distance between them (1)
What is the constant of proportionality, G?
the universal constant of gravity
Describe the properties of a geo-synchronus orbit?
- equitorial orbit
- period is 24 hours
- moving west to east
What advantages does it have in communications
- offers uninterrupted communication between transmitter and receiver (1)
- steerable dish not necessary (1)
What are the benefits of low orbit satellites? What are the features
- cheaper to launch
- require less powerful transmitters
- need multiply satellites
- usually over north pole
- over a new part of earth surface, whoel earth scanned
- see earth in high detail
- imaging
- spying
- monitoring weather
Explain why the time to fall vertically between the plates is independent of the mass of a particle.
- Time to fall (given distance) depends (only) on the distance and acceleration
- g = GM/r2
- g independant on mass
What is escape velocity?
- minimum speed that will allow an object to escape Earth’s graviatational field with no further energy input
Why does a rocket not need the escape velocity to reach their orbit?
- continuous thrust provided
- uses fuel
- less energy needed to acheive orbit
- not leaving the gravitational field
