Test: Energy, Work & Power - 2 - Year 11 MCQ

The conservation of energy principle states that within a closed system, the total energy remains constant over time. This means that the total energy input into the system equals the total energy output from it. In essence, energy cannot be created or destroyed within a closed system; it can only transition between different energy stores.

Sankey diagrams visually represent energy transfers using arrows. These arrows split to show the proportions of energy moving between different components. The width of each arrow corresponds to the amount of energy being transferred. The left side of the arrow symbolizes the energy entering the system, while the straight arrow pointing right depicts the useful energy output. Arrows bending away signify wasted energy.

Work is done when a force is used to move an object over a distance, leading to the transfer of energy from one energy store to another. When a force is applied in the direction of an object's displacement, work is considered to be done as the force acts on the object.

Power is defined as the rate at which work is done or energy is transferred per unit of time. It denotes how quickly energy is transferred or work is performed. Power is crucial in understanding the efficiency and effectiveness of energy transfers within a system.

Efficiency quantifies the proportion of useful power or energy output from a system relative to its total power or energy input. A high efficiency indicates that the majority of transferred energy is utilized effectively, while low efficiency implies that a significant portion of transferred energy is wasted.

Efficiency, expressed as a percentage, is calculated by dividing the useful energy output by the total energy input. This ratio provides a measure of how effectively energy is being utilized within a system.

A high efficiency value indicates that a significant proportion of the transferred energy within a system is being used effectively for useful work. It signifies that the system is operating efficiently and minimizing energy wastage.

Sankey diagrams visually represent energy transfers using arrows that split to show the proportions of energy moving between different components. The width of each arrow corresponds to the amount of energy being transferred, making it an effective tool for visualizing energy flows within a system.

Time plays a crucial role in understanding power, as power is defined as the rate at which energy is transferred per unit of time. It denotes how quickly work is done or energy is transferred within a system, providing insights into the efficiency and effectiveness of energy transfers.

Efficiency quantifies the proportion of useful power or energy output from a system relative to its total power or energy input. It provides a measure of how effectively energy is being utilized within a system, with high efficiency indicating that a significant portion of transferred energy is utilized effectively for useful work.