APM2EA1
Lecture 1 (7 Feb 2017)
Key concepts arising from the lecture:
Note. Vectors are indicated using the bar notation, rather than boldface notation (for instance, a rather than a).
Note. Sections 2.1-2.3 are self-study. Lecture 2 takes place on 9 February 2017
and will cover the remainder of section 2.4 as well as section 2.5.
1. The following statements are equivalent for a system to be in equilibrium:
(a) F = 0
(b) a = 0
(c) v is constant.
2. The following statements are equivalent for a system to be in static equilibrium:
(a) Constant velocity v = 0
(b) ∆r = 0
(c) r is constant.
3. If a particle is at a point A at time t0 , at B at time t1 and at C at time
t2 , then the following requirements must be met in order for the system to
be in equilibrium when the particle experiences uniform velocity in each
time interval:
(a) AB = kBC
(b) t1 − t0 = k (t2 − t1 )
AB
BC
=
,
(c) AB BC where 0 < k ∈ R.
4. If a particle is at a point A and after a time interval of ∆t has elapsed
the particle is at a point B, then the particle is in static equilibrium iff
AB = 0.
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