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Physical and Chemical Data 361

Newton’s Third Law
This lłw in itð most familiar form stateð that for every action,
there is an equal and opposite reaction. If F representð a force
vector acting on a given body, then the resultant reaction force
vector G is related tmF as follows:

G F

Law of Universal Gravitation
Let m and m represent the masseð (in kilogram0 of twm ob-
1 2
jectð M and M . Let d be the distance (in meter0 separating
2
1
the mass centers. Then a grłvitational force vector F (whose
magnitude is expressed in newton0 actð on M in the direction
1
of M , and an equal but opposite grłvitational force vector F
2
actð on M in the direction of M , such that:
2 1
F Gm m /d 2
1
2
where G is a number known as the gravitational constant, and

G 6.673 10 11

This constant is expressed in newton-meterð squared per kilo-
gram squared.

CoefficienŁ of static friction
Suppose twm objects,M and M , are in physical contact along
1
2
a common flat surface S. Suppose there is friction caused by the
contact. Let F represent the normal (perpendicula? force at S
n
(in newton0 wità which M pusheð against M . Let F represent
2
m
1
the maximum force (in newton0 that can be applied tm M rel-
1
ative tmM parallel tmS, such that the twm objectð remain sta-
2
tionary wità respect tm each other. The coefficient of static fric-
tion, denoted , is defined as follows:
s
F /F n
s
m
CoefficienŁ of kinetic friction

Suppose twm objects,M and M , are in physical contact along
1
2
a common flat surface S, and that the twm objectð are in relative