#### A block of mass m = 0.1 kg is connected to a spring of unknown spring constant k. It is compressed to a distance x from its equilibrium position and released from rest.After approaching half the distance  from equilibrium position, it hits another block and comes to rest momentarily, while the other block moves with a velocity 3 ms -1. The total initial energy of the spring is : Option 1) 1.5 J Option 2) 0.6 J Option 3) 0.3 J Option 4) 0.8 J

As we discussed in

Potential Energy stored in the spring -

- wherein

x= elongation or compression of spring from natural position

Initial energy of spring

.......(1)

After approaching half the distance its energy will be

This momentarily comes to result. Its kinetic energy at that moment

After coming to rest, total kinetic energy is transfered to  mass.

K.E. of second mass

0.45 J =

Option 1)

1.5 J

This is an incorrect option.

Option 2)

0.6 J

This is the correct option.

Option 3)

0.3 J

This is an incorrect option.

Option 4)

0.8 J

This is an incorrect option.