The laws of equilibrium for a set of co-planar forces acting on a metre stick were investigated by a student - Leaving Cert Physics - Question 1 - 2013
Question 1
The laws of equilibrium for a set of co-planar forces acting on a metre stick were investigated by a student. She first found the centre of gravity of the metre stic... show full transcript
Worked Solution & Example Answer:The laws of equilibrium for a set of co-planar forces acting on a metre stick were investigated by a student - Leaving Cert Physics - Question 1 - 2013
Step 1
How did the student find the centre of gravity of the metre stick?
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Answer
The student found the centre of gravity by balancing the metre stick horizontally at a point (fulcrum) that allowed it to maintain equilibrium. This was achieved by suspending the entire stick from a string, ensuring the stick was level and stable. The centre of gravity was identified at the 50.3 cm mark, demonstrating that the stick is not uniform and indicating additional materials or weight distribution along the stick.
Step 2
How did the student ensure that the system was at equilibrium?
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To ensure equilibrium, the student hung a set of three weights from the metre stick. She adjusted the positions and magnitudes of these weights until the stick remained horizontal and did not tilt in either direction. The use of two spring balances helped confirm that the upward and downward forces were balanced.
Step 3
Draw a diagram of the experimental arrangement that the student used.
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The diagram would depict the metre stick suspended horizontally from a string at its midpoint, with three weights hung at various positions marked on the stick. Each weight would be indicated with arrows showing the direction of the respective forces acting downward.
Step 4
Calculate the total of the clockwise moments.
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The clockwise moments can be calculated using the formula:
extMoment=extForceimesextDistance
Using the data given, the clockwise moments about the mid-point (50 cm) are calculated from the positions of the forces that act in a clockwise direction.
Step 5
Calculate the total of the anti-clockwise moments.
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Similarly, the anti-clockwise moments are calculated using the same formula as above, but for forces that act against the clockwise direction. The total moment from the upward forces is summed to find the total anti-clockwise moments.
Step 6
Explain how these results verify the laws of equilibrium.
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The laws of equilibrium state that for an object to be in a state of balance, the total clockwise moments must equal the total anti-clockwise moments. By calculating both and finding them equal, it confirms that the forces acting on the metre stick are balanced, thus verifying the conditions required for equilibrium.
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