particular lesson-discuss, justify,
explain, etc)
Language through
learning(Structures)
centre of mass
shape of body
mass of a body
Teaching Plan (Procedure, timing, type, sequence of activities)
I. Activity
«Scrambled sentences»
Make up sentences with the correct word order.
1. out, of, body, this, spread, mass, the, a, single, in, a, all, point, the, which,
is, body, represents.
(
This is the single point in a body which represents all the spread out mass of
a body.
)
2. gravity, produce, on, mass, acts, at, weight, the, centre, of, mass, weight, the,
to, acts,
since.
(
The weight acts at the centre of mass since gravity acts on mass to produce
weight.
)
II. New material
Where is the centre of mass?
position centre of mass depends on
shape of body
this is how the high jumper can have his centre of mass pass under
the bar
but he could still clear the bar
78
The principle of moments
A moment is the turning effect of a force about a point (or pivot). It is defined
as:
M = F • d
Moment = force • perpendicular distance of the force from the turning point.
79
A moment has the unit Nm (Newton meter)
When the force is at right angles (see diagram above), we just multiply the
force by the distance from the force to the pivot.
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