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| A boy in a lift Consider the motion of the boy and take upward direction as positive. By Newton's 2nd Law of motion, ¡@
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| Consider the motion of the lift. By Newton's 2nd Law of motion,
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| Consider the motion of the mass m.
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| From (1) + (2) + (3), we have ¡@¡@¡@ ¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@¡@ We could have the same equation by considering different bodies as a whole ¡@¡@¡@ |
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The pulley system
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| Assume pulleys are light in weight and no friction exists.
Consider m1, m2 and m3 respectively,
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