Fichas
A2 Physics Gravitational fields
Fichas del conjunto (17)
- 1What is the force of gravityAn attractive force between two objects due to their masses
- 2What is the gravitational field strength gAt a point, it is the gravitational force exerted per unit mass on a small object placed at that point
g=F/m or g=GM/r^2 - 3The external field of a uniform spherical mass is the same as thatof an equal point mass at the center of the sphere
- 4Newton's law of gravitationAny two point masses attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of their separation
- 5The equation for Newton's law of gravitation
- 6On or near the surface of the Earth, the gravitational field is...uniform so the value of g is approximately constant. Its value is equal to the acceleration of free fall
- 7Gravitational potentialAt a point is the work done in bringing unit mass from infinity to that point
- 8Equation for gravitational potentialThe sign is negative as gravitational force is always attractive
Decreases in direction of field
- 9Orbital periodTime taken for a satellite to complete one orbit
- 10Kepler's Third LawThe orbital period can be found by equating the centripetal force and the gravitational force
- 11Orbital speed
- 12Geostationary satellitesSatellites that have an orbital period of 24 hours and are used for telecommunications, transitions and for television broadcasting
Launched from equator in the direction of rotation of Earth (East to West) - 13Equation for gravitational potential energy
- 14Describing a gravitational fieldFor an isolated point mass, the gravitational field is spherical in shape with the mass at the center
The gravitational field is described by the field lines. A field line is the path followed by a free unit mass in that gravitational field
A higher density of field lines = a region of stronger field - 15Gravitational potential energy differenceThe work done in moving a mass from one point to another
U final - U initial - 16Escape velocityv^2 = 2GM/r
The speed a satellite needs to get into orbit however not used as it is a huge value and satellites have engines so provide thrust to reach height of orbit - 17Why do astronauts report feeling weightless even under Earth's gravitational fieldGravitational force provides the centripetal force: the gravitational force is equal to the centripetal force
This means the difference between the two forces is 0 so zero g
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- AS level Physics Fichas sobre A2 Physics Gravitational fields, creado por Sean Byrne el 03/09/2017.
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- Sean Byrne
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