Mesosaurus lived in freshwater lakes and ponds. Elongated and slim, it measured about 3.3 feet long. The skull and tail were both long and narrow, and the animal probably undulated through the water as it fed on small crustaceans and other prey with its jaws, which were full of long, thin, pointed teeth.
Answer:
Choice A: Approximately joules.
Explanation:
Apply the famous mass-energy equivalence equation to find the energy that correspond to the kilograms of mass.
,
where
- stands for energy,
- stands for mass, and
- is the speed of light in vacuum.
The speed of light in vacuum is a constant. However, finding the right units for this value can simplify the calculations a lot. What should be the unit of ?
The mass given is in the appropriate SI unit:
Mass is in kilograms.
Thus, proceed with the speed of light in SI units. The SI unit for speed is meters per second. For the speed of light, .
Apply the mass-energy equivalence:
.
The unit of energy is not in joules. Don't be alerted. Consider the definition of a joule of energy. One joule is the work done on an object when a force of one newton acts on the object in the direction of the force through the distance of one meter. (English Wikipedia.)
.
However, a force of one newton is defined as the force required to accelerated an object with a mass of one kilogram (not gram) at a rate of one meter per second squared. (English Wikipedia.)
.
In other words, the mass defect here is also .