Topic 12: Gravitational Fields
1.2 Specification notice:
Mathematical skills that could be developed in this topic include
sketching relationships that are modelled by y = k/x, y = k/x2.
12.Q Exam questions
12.174 understand that a gravitational field (force field) is
defined as a region where a mass experiences a force
Define gravitational field (force field)? A region of space where a mass
experiences a gravitational force
12.175 understand that gravitational field strength is defined
𝐹
as 𝑔 = and be able to use this equation
𝑚
What is Gravitational Field Strength and ● It is the amount of force something would feel
what is the equation for it? (uniform field) per unit mass (Nkg-1).
𝐹
𝑔=
𝑚
g is the gravitational field strength (Nkg-1), F is the force
due to gravity (N), m is the mass of the object (kg)
, 𝐺𝑚1 𝑚2
12.176 be able to use the equation 𝐹 = (Newton’s law of
𝑟2
universal gravitation)
What is the definition of Newton’s Law of
Universal Gravitation and whats its The gravitational force F between two
equation?
masses (m1 and m2) is directly proportional
to the product of the masses and inversely
proportional to the square of the distance
between them
𝐺𝑚1 𝑚2 𝐺𝑀𝑚
𝐹= or 𝐹 =
𝑟2 𝑟2
F is the force between the two objects (N), G
is the gravitational constant 6.67x10-11 (also
known as big G), m1 and m2 are the masses
of the two objects are r is the distance
between the centre of masses (m).
Big M is the mass that creates the g field
A common mistake in exams is to forget to
add together the distance from the surface
of the planet and its radius to obtain the
value of r.
1.2 Specification notice:
Mathematical skills that could be developed in this topic include
sketching relationships that are modelled by y = k/x, y = k/x2.
12.Q Exam questions
12.174 understand that a gravitational field (force field) is
defined as a region where a mass experiences a force
Define gravitational field (force field)? A region of space where a mass
experiences a gravitational force
12.175 understand that gravitational field strength is defined
𝐹
as 𝑔 = and be able to use this equation
𝑚
What is Gravitational Field Strength and ● It is the amount of force something would feel
what is the equation for it? (uniform field) per unit mass (Nkg-1).
𝐹
𝑔=
𝑚
g is the gravitational field strength (Nkg-1), F is the force
due to gravity (N), m is the mass of the object (kg)
, 𝐺𝑚1 𝑚2
12.176 be able to use the equation 𝐹 = (Newton’s law of
𝑟2
universal gravitation)
What is the definition of Newton’s Law of
Universal Gravitation and whats its The gravitational force F between two
equation?
masses (m1 and m2) is directly proportional
to the product of the masses and inversely
proportional to the square of the distance
between them
𝐺𝑚1 𝑚2 𝐺𝑀𝑚
𝐹= or 𝐹 =
𝑟2 𝑟2
F is the force between the two objects (N), G
is the gravitational constant 6.67x10-11 (also
known as big G), m1 and m2 are the masses
of the two objects are r is the distance
between the centre of masses (m).
Big M is the mass that creates the g field
A common mistake in exams is to forget to
add together the distance from the surface
of the planet and its radius to obtain the
value of r.
