Polymers like thermoplastic polymers can be recycled because they can be melted easily but thermosetting polymer can not be recycled because of their high melting point. Ceramics due to their high melting point are not recycled.
Thermoplastic composites can be recycled but thermoseting composites are not recycled. Composites are mix of two or more type of material having different physical and chemical properties.
As the surface is horizontal, the only change in energy will be the change in kinetic energy, as the box comes to an stop after compressing the spring.
As we know that the surface is frictionless also, this change in kinetic energy must be equal to the change in the elastic potential energy of the spring.
So we can write the following equality:
where
and
Simplifying and replacing by the values, we get:
Solving for k:
k = 3594.7 N/m
b)
For this part, we can just apply the same equality, replacing the value of k by the one we got, and solving for the initial speed v: