A balanced lever has two weights on it, one with mass #2 kg# and one with mass #8 kg#. If the first weight is # 4 m# from the fulcrum, how far is the second weight from the fulcrum?
The concept that comes into use here is torque. For the lever to not tip over or rotate, it must have a net torque of zero.
Now, the formula of torque is
Take an example to understand, if we hold a stick and attach a weight at the front of the stick, it doesn't seem too heavy but if we move the weight to the end of the stick, it seems a lot heavier. This is because the torque increases.
Now for the torque to be same,
The first block weighs 2 kg and exerts approximately
The first block weighs 8 kg and exerts approximately
Putting this in the formula,
We get that x= 1m and hence it must be placed at a distance of 1m