A block of mass ' $\mathrm{m}$ ' is connected to another block of mass ' $\mathrm{M}$ ' by a spring…

A block of mass ' $\mathrm{m}$ ' is connected to another block of mass ' $\mathrm{M}$ ' by a spring (massless) of spring constant ' $\mathrm{k}$ '. The blocks are kept on a smooth horizontal plane. Initially the blocks are at rest and the spring is unstretched. Then a constant force '$\mathrm{F}$' starts acting on the block of mass '$\mathrm{M}$' to pull it. Find the force on the block of mass '$\mathrm{m}$'
  1. $\frac{\mathrm{mF}}{\mathrm{M}}$
  2. $\frac{\mathrm{(M+m) F}}{\mathrm{m}}$
  3. $\frac{\mathrm{m F}}{\mathrm{(m+M)}}$
  4. $\frac{\mathrm{MF}}{(\mathrm{m}+\mathrm{M})}$

Solution

$\mathrm{Kx}=\mathrm{ma}=\frac{\mathrm{mF}}{\mathrm{m}+\mathrm{M}}$

Asked in: JEE Main 2007

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