Solar collectors are parts of . a. passive solar heating systems b. active solar heating systems c. internal combustion engines d. external combustion engines

b. active solar heating systems

Explanation:

A solar collector is a device that collects and/or concentrates solar radiation from the Sun. These devices are primarily used for active solar heating and allow for the heating of water for personal use.

-ZERO-   No 17.6 pound Earth-bound cat is going to be able to jump to the top of a 6 feet 7 inch bookshelf unassisted!  Someone should call the SPCA on the writer of this textbook question ;-)

Assuming that this overweight cat is content being placed in such a lofty position, your professor probably wants the answer of 156.8 Joules

Mass x  Acceleration of Gravity (on Earth) x elevation = Potential Energy

8 Kg x 9.8 m/s2  x 2 m  = 156.8 J