Two blocks \(M_1\) and \(M_2\) having equal mass are free to move on a horizontal frictionless surface. \(M_2\) is attached to a massless spring as shown in figure. Initially, \(M_2\) is at rest and \(M_1\) is moving toward \(M_2\) with speed \(v \) and collides head-on with \(M_2.\)
Consider the following given statements:
| (a). | while spring is fully compressed, all the kinetic energy of \(M_1\) is stored as potential energy of spring. |
| (b). | while spring is fully compressed, the system's momentum is not conserved, though final momentum is equal to initial momentum. |
| (c). | if spring is massless, the final state of the \(M_1\) is state of rest. |
| (d). | if the surface on which blocks are moving has friction, then collision cannot be elastic. |
| 1. | only (a) |
| 2. | (a), (b) |
| 3. | (b), (c) |
| 4. | (c), (d) |
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