A type of matter made up of a combination of elements is called a compound. for example table salt, is made up of two elements that by themselves are lethal but chemically combined cancel each other out there for becoming edible.
Since there are no choices, then this question calls for open-ended answers. Facts-based science must have proven underlying laws that support inferences such as Coulomb's Law, Kinetic Theory of Matter and many more. On the other hand, examples of science that focus on personal belief is philosophy. This depends on the perspective of known philosophers. An example would be Sigmund Freud who proposed the theory of 3 personalities. Although it is more on personal beliefs, this is used as a foundation in the study of psychology.
Initially, the experiment has only potential energy (since total energy is the sum of kinetic and potential energy). And at the end, the experment has only kinetic energy.
M = mass of the first sphere = 10 kg
m = mass of the second sphere = 8 kg
V = initial velocity of the first sphere before collision = 10 m/s
v = initial velocity of the second sphere before collision = 0 m/s
V' = final velocity of the first sphere after collision = ?
v' = final velocity of the second sphere after collision = 4 m/s
using conservation of momentum
M V + m v = M V' + m v'
(10) (10) + (8) (0) = (10) V' + (8) (4)
100 = (10) V' + 32
(10) V' = 68
V' = 6.8 m/s
