Q. A light spring balance hangs from the hook of the other light spring balance and a block of mass M kg hangs from the former one. Then the true statement about the scale reading is
Rajasthan PMTRajasthan PMT 2008Laws of Motion
Solution:
The arrangement is shown in figure.
Now draw the free body diagram of the spring balances and block.
For equilibrium of block, $ {{T}_{1}}=Mg $ where $ {{T}_{1}}= $ Reading of $ {{S}_{2}} $ For equilibrium of $ {{S}_{2}},\,\,{{T}_{2}}={{T}_{1}} $ where $ {{T}_{2}}= $ Reading of $ {{S}_{1}} $ For equilibrium of $ {{S}_{1}},\,\,{{T}_{2}}={{T}_{3}} $ Hence, $ {{T}_{1}}={{T}_{2}}=Mg $ So, both scales read $ M\,\,kg $ .
