O-LevelPhysicsForces5054/11 · May/June 2011 · Q91 Mark
A student finds the centre of mass of a triangular lamina PQR. He drills a small hole at Q. He suspends the lamina from a pin through the hole at Q so that the lamina swings freely. He then hangs a plumb-line from the pin at Q, as shown. He marks the position of the plumb-line on the lamina. To determine the location of the centre of mass, the student then repeats the experiment but with one change. What is the change?
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
AHe suspends the lamina from the hole at Q, with R on the left and P on the right.
BHe suspends the lamina from a pin through a hole at R.
CHe uses a heavier weight on the plumb-line.
DHe uses a longer plumb-line.
✓ Correct answer
B: He suspends the lamina from a pin through a hole at R.
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