Final answer:
In a perfectly elastic collision, the height to which a package rebounds can be calculated using the conservation of energy, equating the kinetic energy at the collision to the potential energy at the rebound's peak.
Step-by-step explanation:
The question is regarding a perfectly elastic collision, which is a concept in physics where two objects collide and bounce off each other without losing any kinetic energy. In the case of a perfectly elastic collision where a package of mass m rebounds, the rebound height can be determined using conservation of energy.
The kinetic energy of the package at the moment of collision is entirely converted to potential energy at the peak of its rebound, allowing us to calculate the maximum height it reaches.
The formula for gravitational potential energy is PE = mgh (where m is the mass, g is the acceleration due to gravity, and h is the height), and for kinetic energy, it's KE = ½mv² (where v is the velocity). Since KE before the collision will equal the PE at the rebound's peak height, we can equate ½mv² = mgh and solve for h, giving h = v² / (2g).