The Turning Effect of Forces

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The Turning Effect of Forces

• You should be able to
• state what the centre of gravity of an object is.
• describe a simple experiment to determine the
  centre of gravity of an object.
• define and apply the moment of force.
• apply the principle of moments to solve
  problems, including the human forearm.

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The Turning Effect of Forces
Describe an experiment to find the centre of
gravity of an object.
1. Suspend object from a point 2. Use plumb
line to find the vertical line and mark it on
with a pencil 3. Hang from another point and draw
another vertical line 4. Where the lines
intersect gives position of centre of gravity 5.
Check your centre of gravity by choosing another
point and repeating.
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The Turning Effect of Forces
Centre of Gravity the point where the weight of
an object can be considered to act.
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The Turning Effect of Forces
Centre of Gravity
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The Turning Effect of Forces
Define and apply the moment of force
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The Turning Effect of Forces
Define and apply the moment of force
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The Turning Effect of Forces
Define and apply the moment of force
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The Turning Effect of Forces
Define and apply the moment of force
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The Turning Effect of Forces
Define and apply the moment of force

• Use the equipment available to find
• The mass of the rule
• The mass of the unknown weight

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The Turning Effect of Forces
Define and apply the moment of force
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The Turning Effect of Forces
Define and apply the moment of force
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The Turning Effect of Forces
Define and apply the moment of force
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The Turning Effect of Forces

• You should be able to
• define and apply the torque of a couple
• explain that both the net force and net moment
  on an object in equilibrium is zero
• apply the principle of moments to solve
• problems where the perpendicular force has to be
  calculated.

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The Turning Effect of Forces

• Couple

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The Turning Effect of Forces
What is the significance of this diagram ?
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The Turning Effect of Forces
What is the counterweight (W) required to balance
the light crane arm shown in diagram ?
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The Turning Effect of Forces
What is the tension (T) in the cable shown in
diagram ?
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The Turning Effect of Forces
What is the tension (T) in the cable shown in
diagram?
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• Typical loading diagram