7.30.Model: The two blocks form a system of interacting objects. Visualize:Please refer to Figure P7.30. Solve:It is possible that the left-hand block (Block L) is accelerating down the slope faster than the right-hand block (Block R), causing the string to be slack (zero tension). If that were the case, we would get a zero or negative answer for the tension in the string. Newton’s first law applied to the y-direction on Block L yields ()()LLGLLL0cos20cos20==−° ⇒=°∑yFnFnm gTherefore ()()()()()2kkLLLcos200.201.0 kg9.80 m/scos201.84 Nfm gμ=° =° =A similar analysis of the vertical forces on Block R gives ()kR1.84 Nf=as well. Using Newton’s second law in
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