a lever has a total length of 12 meters with a fulcrum at the exact center of the lever. which best…

Explanation:

Step1: Calculate initial situation

The lever has a total length of 12 meters with the fulcrum at the center. So the effort - arm and the resistance - arm are both 6 meters, and the initial mechanical advantage (MA) is 1 (since MA = effort - arm length/resistance - arm length, and 6/6 = 1).

Step2: Determine goal for double MA

We want to double the mechanical advantage to 2. Let the effort - arm be $L_{e}$ and the resistance - arm be $L_{r}$. We know that $MA=\frac{L_{e}}{L_{r}} = 2$, and $L_{e}+L_{r}=12$. Substituting $L_{e}=2L_{r}$ into $L_{e}+L_{r}=12$, we get $2L_{r}+L_{r}=12$, so $3L_{r}=12$ and $L_{r} = 4$ meters, $L_{e}=8$ meters.

Step3: Analyze fulcrum movement

Initially, the fulcrum is at the 6 - meter mark. To get an effort - arm of 8 meters and a resistance - arm of 4 meters, we need to move the fulcrum 2 meters away from the side on which the force is applied.

Answer:

Move the fulcrum 2 meters away from the side on which the force is applied.