Here, a four-seater merry-go-round is fitted with four spring balances. Sit in the seat and hold the handle before rotating the merry-go-round.

What did you observe? 
While rotating, there is deflection of the pointer in the spring balance.

The science behind it :
Every rotating particle is subjected to an outward force called the Centrifugal force. When we are rotating in the merry-go-round, we are also subjected to the centrifugal force and we tend to overcome it by holding the handle rigidly.