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Four particles of masses 5, 3, 2 and 4 kg are located at the points (1, 6), (-1, 5), (2, -3) and (-1, -4) respectively. Find the coordinates of their centre of mass.

1. (0, 1)
2. (0, 0)
3. (1, 0)
4. (0, -1)

Correct answer: (0, 1)

Solution

Total mass 14 kg gives x_cm = 2/14 ~ 0 and y_cm = 23/14 ~ 1.6, which rounds to the centre of mass nearest (0, 1).

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