The vacuum cleaner's efficiency is calculated as 37.5%. This is determined by the ratio of useful energy output (45J) to total energy input (120J). Real-world devices typically have efficiencies less than 100% due to energy losses.
The vacuum cleaner's efficiency can be calculated using the formula: Efficiency = (Useful energy output / Total energy input) x 100%. In this scenario, the vacuum cleaner used a total of 120 joules of electrical energy, but only 45 joules of that energy were used for the useful task of pulling in air. Therefore, the vacuum cleaner's efficiency would be calculated as: Efficiency = (45 J / 120 J) x 100% = 37.5%.
It's important to understand that real machines do not achieve 100% efficiency because some energy is always lost as heat due to friction and air resistance. As such, the vacuum cleaner's efficiency of 37.5% fits within expected bounds for real-world devices.
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B. Hibernation
C. Migration
D. Symbiosis
their speed, which is the speed of light