Gravitational field strength is a vector quantity. In which direction does it act?

Always towards the centre of the body producing the field (the same direction as the gravitational field lines).

True or False? Gravitational field strength decreases linearly with distance from a point mass.

False. g is inversely proportional to r 2 (an inverse square law), so it decreases much faster than a linear relationship.

g can be treated as approximately constant close to the Earth's surface because the Earth's radius, R , is much greater than the .......... above the surface, h ( R ≫ h ).

g can be treated as approximately constant close to the Earth's surface because the Earth's radius, R , is much greater than the height above the surface, h ( R ≫ h ).

True or False? Gravitational field strength at the top of Mount Everest is more than 10% less than at the Earth's surface.

False. g at the top of Everest is only about 0.3% less than at the surface, since Everest's height is negligible compared with the Earth's radius.

A LevelPhysicsCambridge (CIE)Flashcards13. Gravitational FieldsGravitational Field of a Point Mass

Gravitational Field of a Point Mass (Cambridge (CIE) A Level Physics): Flashcards

Exam code: 9702

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FrontGravitational Field Strength
Define gravitational field strength at a point.
FrontGravitational Field Strength
State the equation for gravitational field strength due to a point mass M at distance r, and define each symbol.
BackGravitational Field Strength
$g = \frac{G M}{r^{2}}$
g = gravitational field strength (N kg^-1)
G = Newton's gravitational constant
M = mass of the body producing the field (kg)
r = distance from the point mass to the position in the field (m)

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Cards in this collection (9)

Define gravitational field strength at a point.
The force per unit mass acting on a small mass at that point: $g = \frac{F}{m}$
State the equation for gravitational field strength due to a point mass M at distance r, and define each symbol.
$g = \frac{G M}{r^{2}}$
- g = gravitational field strength (N kg^-1)
- G = Newton's gravitational constant
- M = mass of the body producing the field (kg)
- r = distance from the point mass to the position in the field (m)
Gravitational field strength is a vector quantity. In which direction does it act?
Always towards the centre of the body producing the field (the same direction as the gravitational field lines).
What is the difference between the equations $g = \frac{F}{m}$ and $g = \frac{G M}{r^{2}}$ ?
$g = \frac{F}{m}$ gives the field strength at a point, from the force acting on a small test mass there
- $g = \frac{G M}{r^{2}}$ gives the field strength due to a point mass, derived by equating this force with Newton's law of gravitation
True or False?
Gravitational field strength decreases linearly with distance from a point mass.
False.
g is inversely proportional to r² (an inverse square law), so it decreases much faster than a linear relationship.
What is the value of gravitational field strength g close to the Earth's surface, within the Earth's atmosphere?
g = 9.81 N kg^-1
g can be treated as approximately constant close to the Earth's surface because the Earth's radius, R, is much greater than the .......... above the surface, h (R ≫ h).
g can be treated as approximately constant close to the Earth's surface because the Earth's radius, R, is much greater than the height above the surface, h (R ≫ h).
State the equation for gravitational field strength g at a height h above the Earth's surface.
$g = \frac{G M}{{(R + h)}^{2}}$
True or False?
Gravitational field strength at the top of Mount Everest is more than 10% less than at the Earth's surface.
False.
g at the top of Everest is only about 0.3% less than at the surface, since Everest's height is negligible compared with the Earth's radius.

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