# A balanced lever has two weights on it, one with mass 4 kg and one with mass 2 kg. If the first weight is  9 m from the fulcrum, how far is the second weight from the fulcrum?

Apr 1, 2016

$18 \text{m}$

#### Explanation:

To balance the lever, the torque about the fulcrum must be zero.

In this question, we have

• ${M}_{1} = 4 \text{kg}$
• $a = 9 \text{m}$
• ${M}_{2} = 2 \text{kg}$

We want to find $b$.

Therefore,

$\left(4 \text{kg") * (9 "m") = (2 "kg}\right) \cdot b$

b = frac{(4 "kg") * (9 "m")}{2 "kg"}

$= 18 \text{m}$