9. A uniform metre scale can be balanced at the 70.0 cm mark when a mass of 0.05 kg is hung from the 94.0 cm mark.
(i) Draw a diagram showing the arrangement.
(ii) Find the mass of the metre scale.

10. A boy of mass 30 kg is sitting at a distance of 2 m from the middle of a see-saw. Where should a boy of mass 40 kg sit so as to balance the sea-saw?

Dear Student,

Please find below the solution of the question number 10 as here no question with 7 is found :

For balance moment should be equal for both of them, so we have
$$\begin{gathered} r_1{F}_1=r_2{F}_2 \\ 2\times 30=r_2\times 40 \\ {r}_2=\frac{60}{40}=1.5 \text{m} \end{gathered}$$
The other by need to seat 1.5 m away from the centre.

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