Answer:34 cm
Explanation:
Given
mass of meter stick m=80 gm
stick is balanced when support is placed at 51 cm mark
Let us take 5 gm tack is placed at x cm on meter stick so that balancing occurs at x=50 cm mark
balancing torque
[tex]80\times 10^{-3}(51-50)=5\times 10^{-3}(50-x)[/tex]
[tex]80=5(50-x)[/tex]
[tex]80=250-5x[/tex]
[tex]5x=170[/tex]
[tex]x=\frac{170}{5}[/tex]
[tex]x=34 cm[/tex]