- 2017 JEE Main Physics Question 13:
A block of mass m is connected to another block of mass M by a spring (massless) of spring constant 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 F starts acting on the block of mass M.
(A) Find the maximum extension of the spring.
Let the maximum extension of the spring be x. The total mechanical energy of the system is conserved. The initial mechanical energy of the system is zero. The final mechanical energy of the system is $\frac{1}{2}kx^2 + \frac{1}{2}Mv^2$. Equating the two, we get $x = \frac{F}{k}$.
(B) Find the acceleration of the centre of mass of the system.
The centre of mass of the system is at rest initially. The net external force acting on the system is $F$. So, the acceleration of the centre of mass of the system is $\frac{F}{m+M}$.
(C) Find the maximum velocity of the block of mass
