The sum of gravitational potential energy and kinetic energy is called mechanical energy. Use Figure 2 to find the mechanical energy
of an idealized pendulum at a variety of times in its cycle. Identify any pattern you
notice in the values of mechanical energy.

Explanation:

Mechanical energy = Gravitational potential energy + kinetic energy

Time            Gravitational potential energy        kinetic energy         Total ME

0                                    4                                                0                        4

2                                     2                                               2                        4

4                                     0                                               4                        4

6                                     2                                               2                        4

8                                     4                                               0                        4

and so on  

We see that total mechanical energy is always 4 which is constant .

So gravitational and kinetic energy changes cyclically but total mechanical energy is constant .

answer is: naturally occurring solid, inorganic compound or element is mineral.

minerals usually have crystalline form, that means than crystal constituents (atoms, molecules or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions.

for example magnetite is a mineral of iron oxide (fe₂o₃).

calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (caco₃).

dolomite is an   carbonate mineral composed of calcium magnesium carbonate (camg(co₃)₂).