A heavy freight elevator cabin descends down a shaft towards an emergency spring-buffer system.

Complete the sentences. Choose answers from the box:

[ chemical | elastic potential | gravitational potential | kinetic | thermal ]

• As the elevator cabin falls, there is a decrease in its ____________________ energy.
• As the elevator cabin falls, there is an increase in its ____________________ energy.

As the elevator cabin lands on the buffer system, each heavy-duty spring compresses by 0.15 m. The spring constant of each spring is $120,000N/m$.

Calculate the elastic potential energy stored by each spring.

Use the equation:

$$elastic\; potential\; energy=0.5\times spring\; constant\times (compression{)}^2$$

There are 16 of these buffer springs at the bottom of the shaft.

Calculate the total energy stored by the 16 springs when each spring is compressed by 0.15 m. Use your answer from Part (b).

The kinetic energy of the elevator cabin just as it contacts the buffer springs is $24,500J$. The maximum kinetic energy of the elevator cabin as it rebounds upward is 34% of its kinetic energy just as it landed.

Calculate the maximum kinetic energy of the elevator cabin immediately after the rebound begins.

Why is the kinetic energy of the elevator cabin after it rebounds less than its kinetic energy just as it landed? Select one option:

• Energy is not conserved.
• Energy is transferred to the surroundings.
• The buffer springs transfer energy to the elevator cabin.