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Starter
Unscramble these words:
gdra tthsru crtiinof ytivrga
Here is a common see-saw, draw a diagram showing whereyou would
sit if you had a friend who was much shorter andlighter than you on
the other side and you want the see-sawto balance!
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Levers
Effort
Load
Pivot
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A force acting on an object can cause it to turn abouta
pivot.
What happens to the see-saw when a force is applied
on the left-hand side?
Does the seesaw turn? If so, clockwise or anti-clockwise?
pivot
pivot
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The left-hand side of the see-saw moves downwardswhen a force is
applied to it this is an anticlockwise
turn.
The turning effect of aforce is called amoment.
pivot
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A spanner is a lever that can be used to unscrew a nut.
force
pivot
distance
from forceto pivot
If the moment is big enough it will unscrew the nut.
If not, there are two ways of increasing the moment.
The spanner exerts a moment or turning force on the
nut.
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1.Increase the distancefrom the force to the pivotapply the
force at the end or use a longer spanner.
force
If the same force is applied over a greater distance,
a larger momentis produced.
pivot
distance
from forceto pivot
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2. Increase the forceappliedpush/pull harder or get someone
stronger to do it!
force
If a greater forceis applied over the same distance,
a larger momentis produced.
pivot
distance
from forceto pivot
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Levers
Consider a situation where Miss Welfare is trying tounscrew a
nut using a spanner:
The spanner exerts a MOMENT or TURNING FORCE on thenut. If the
moment is big enough it will UNSCREW the nut!
If the moment is not big enough how could Miss Welfareincrease
the moment (turning force)?
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Levers and moments
There are two ways to increase a moment:
Increase the DISTANCE fromthe pivot (get a longer spanner)
OR
Increase the FORCE applied (geta strong man!)
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The equation (Learn this!)
Moment = Force x Distance from pivot
N/cmor N/m
Newtons
cm or m
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Test your knowledge!
Complete questions on the whiteboard
Youll need acalculator!
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To finish!
SPLAT!
Split into two teams BLUES andREDs
The team with the most correctanswers wins 3 points each!
