Chapter 11.6, Problem 2P

To determine

How far from the fulcrum should an 80-lb weight be placed to balance the lever?

Answer to Problem 2P

7.5ft

Explanation of Solution

Given Information:

An 120-lb weight is placed on a lever, 5ft from the fulcurm.

Concept Used:

• Inverse variation is used.
• The weight of an object on a lever and its distance from the fulcrum are in inverse variation.
• The product of the weight of the object and its distance from the fulcrum is always constant.

Calculation:

Let x be the distance of object of weight 120-lb.

And an 120-lb weight is placed on a lever, 5ft from the fulcurm.

  $\begin{array}{c}weigh{t}_1\cdot dis\tan c{e}_1=weigh{t}_2\cdot dis\tan c{e}_2\\ So120\cdot 5=80\cdot x\\ 600=80x\\ x=\frac{600}{80}\\ x=7.5\end{array}$

7.5ft far from the fulcrum an 80-lb weight be placed to balance the lever