A father and his young son get on a teeter-totter. The son sits 2 m fromthe center, but the father has to sit closer to balance. Where does the father have to sit to balance the teeter-totter if he weighs 4 times as much as his son?

The distance of the father from the center is  

Explanation:

From the question we are told that

    The distance of the son from the center is  

Let the mass of the son be  

     then the mass of the father is  

Now for the teeter-totter to be balanced the torque due to the weight of the father must be equal to the torque due to the weight the son, this is mathematically represented as

Where   is the torque of the son which is mathematically represented as

while is the torque of the father which is mathematically represented as

=>    

 So

substituting values

 =>