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A see-saw of length 6m is pivoted at its...

A see-saw of length 6m is pivoted at its centre. A child (A) of mass 20 kg is sitting at one end of the see-saw. Where should anolther child (B) of mass 30 kg, sit, so that the see saw is balanced?

A

1m

B

1.5m

C

2 m

D

2.5 m

Text Solution

Verified by Experts

The correct Answer is:
C
Since `m_(B) gt m_(A)` the child B should sit nearer to the fulcrum , to balance the see- saw .
Let x be the distance of B from the fulcrum

`F_(1) = 20 g and F_(2) = 30 g`
[ Here g = acceleration due to gravity and not gram ]
`:.` Moment of `F_(1)` about C
`=20gxx3=60g` (anticlockwise)
Moment of `F_(2)` about C = (30 g) `xx` (clockwise)
`:.` For equilibrium , 60 g = 30gx
`:. x = 2 m `
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