Answer:
4. both blocks will both have the same amount of kinetic energy.
Explanation:
When the blocks are released free from the compression force, the spring exerts equal and opposite force on each block but the block with heavier (double) mass will attain slower ( half ) speed as compared to the lighter block according to the law of inertia. This works in synchronization to energy conservation.
Spring force is given as:
[tex]F=k.\Delta x[/tex]
where: [tex]\Delta x=[/tex] length of compression in the spring
We know kinetic energy is given by:
[tex]KE=\frac{1}{2} m.v^2[/tex]
Hence the kinetic energy of both the blocks is equal when they are released to move free.