The unit of energy is the Joule.
If the grass is at the base of the energy pyramid and 90% of the energy is lost at each trophic level, the amount of energy available for the hawk would be 10% of the 10,000 units, which equals 1,000 units of energy.
The amount of energy released when nutrients are broken down is measured in units called kilocalories (kcal) or joules (J). These units quantify the energy content of foods and are commonly used to represent the caloric value of food.
The unit used to express the amount of thermal energy is the joule, which is also the standard unit of energy in the International System of Units (SI).
Its the exact amount without loosing any in the process. This process is called "The Law of Conservation of Energy".
Power is energy divided by time. Solving for energy, energy is power multiplied by time. Work is closely related to energy - work is the amount of energy transferred.
The difference in energy is typically expressed in units like joules (J) or electronvolts (eV). These units represent the amount of work needed to move an object or particle through a potential difference.
Work and energy use the same units; but the term "work" is used in the sense of "transfer of energy" (amount of energy transferred).
Energy is typically measured in units of joules (J), which represent the amount of work done by a force to move an object over a distance. Other common units for energy include calories and electronvolts (eV).
The energy of a fuel is often referred to as its calorific value or heating value, which indicates the amount of energy released when the fuel is burned. This energy is typically measured in units such as kilojoules or British thermal units (BTUs).
A Joule is a derived unit of energy, work, or amount of heat in the International System of Units. It contains no water.
Quantum
The metric unit for potential energy is the joule (J). It is the amount of energy an object has due to its position or state.