The volume of a rectangular bar is given by the formula:
![V=h* l^2](https://img.qammunity.org/2023/formulas/mathematics/college/y6lpisnrqo8cnxfjsgdq8y1ka2tmhdghnq.png)
Where l is the length and h is the height. if we multiply the height of the bar by 1/3, we get:
![hnew=(1)/(3)h](https://img.qammunity.org/2023/formulas/mathematics/college/j8f47urpk0r3qfmuy6dq0j62c26onke4e6.png)
By replacing this new height in the formula of the volume of the bar, we get:
![Vnew=(1)/(3)h* l^2](https://img.qammunity.org/2023/formulas/mathematics/college/39tc144xldht4kqfcawk7wwr4gkmtm5j8c.png)
As we can see, when we multiply the height by 1/3 the same happens with the Volume, this means that the volume of the second bar (after taking 1/3 of its height) is one-third the volume of the first bar. Then the volume of the bar decreases.