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Questions and Answers
What is the efficiency of a power plant that produces 25 MJ of useful energy from an input of 100 MJ?
What is the efficiency of a power plant that produces 25 MJ of useful energy from an input of 100 MJ?
- 25% (correct)
- 75%
- 100%
- 50%
Which of the following energy sources is classified as renewable?
Which of the following energy sources is classified as renewable?
- Coal
- Natural Gas
- Nuclear
- Wind (correct)
If a power plant has an efficiency of 60% and produces 150 MJ of useful energy, what was the total energy input?
If a power plant has an efficiency of 60% and produces 150 MJ of useful energy, what was the total energy input?
- 100 MJ
- 180 MJ
- 90 MJ
- 250 MJ (correct)
How much energy does a wind turbine producing 2 MW generate in 5 hours?
How much energy does a wind turbine producing 2 MW generate in 5 hours?
What is a major environmental impact of fossil fuel power plants?
What is a major environmental impact of fossil fuel power plants?
What is the total mechanical energy of a 2 kg object at a height of 10 m if it is at rest?
What is the total mechanical energy of a 2 kg object at a height of 10 m if it is at rest?
How is power defined in the context of energy transfer?
How is power defined in the context of energy transfer?
What is the correct formula for calculating kinetic energy?
What is the correct formula for calculating kinetic energy?
Calculate the potential energy of a 1000 kg boulder sitting at a height of 5 m.
Calculate the potential energy of a 1000 kg boulder sitting at a height of 5 m.
If a car accelerates from rest at 4 m/s² for 6 seconds, what is its final velocity?
If a car accelerates from rest at 4 m/s² for 6 seconds, what is its final velocity?
What does the unit of power, watt (W), represent?
What does the unit of power, watt (W), represent?
What is the acceleration of an object if its velocity changes from 10 m/s to 20 m/s in 5 seconds?
What is the acceleration of an object if its velocity changes from 10 m/s to 20 m/s in 5 seconds?
What is the relationship between speed and velocity?
What is the relationship between speed and velocity?
Flashcards
Energy Sources
Energy Sources
Different types of materials used to produce energy, including fossil fuels, nuclear, hydroelectric, solar, and wind.
Efficiency
Efficiency
The ratio of useful output energy to the total energy input expressed as a percentage.
Efficiency Formula
Efficiency Formula
The formula to calculate efficiency: Efficiency = (Useful Energy Output / Total Energy Input) × 100%.
Power Plants
Power Plants
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Wind Turbine Energy Production
Wind Turbine Energy Production
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Conservation of Energy
Conservation of Energy
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Mechanical Energy
Mechanical Energy
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Kinetic Energy (KE)
Kinetic Energy (KE)
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Potential Energy (PE)
Potential Energy (PE)
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Power
Power
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Unit of Power
Unit of Power
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Displacement
Displacement
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Acceleration (a)
Acceleration (a)
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Study Notes
Mechanical Energy and Power
- Energy Conservation: Energy transformations, not creation or destruction.
- Mechanical Energy: Sum of kinetic and potential energy.
- Kinetic Energy (KE): Energy of motion. Formula: KE = ½mv².
- Potential Energy (PE): Stored energy due to position. Formula: PE = mgh
- Total Mechanical Energy: Emech = KE + PE
- Power: Rate of energy transfer. Formula: P = ΔE/Δt
- Power Unit: Watt (W), 1 W = 1 J/s
- Energy Units: Joules (J), kilowatt-hours (kWh), 1 kWh = 3.6 MJ
- Work: Energy transferred by force. Formula: W = Fd cos θ
Example Problems: Mechanical Energy
- Kinetic Energy: Calculate KE of 1000 kg car at 20 m/s. Answer: 200,000 J
- Potential Energy: Find PE of 2 kg object at 10 m height. Answer: 196 J
- Power: Calculate power to lift 500 kg box 5 m in 10 seconds. Answer: 2,450 W
Motion
- Displacement (Δx): Change in position.
- Speed vs. Velocity: Velocity includes direction; speed does not.
- Acceleration (a): Rate of change of velocity. Formula: a = Δv/Δt
- Equations of Motion (constant acceleration):
- v = v0 + at
- x = x0 + v0t + ½at²
- v² = v0² + 2a(x - x0)
Example Problems: Motion
- Acceleration: Find final velocity of a car accelerating from rest at 3 m/s² for 5 seconds. Answer: 15 m/s
- Free Fall: Time for a ball dropped from 20 m to hit the ground. Answer approximately 2.02 s
- Roller Coaster: Find initial velocity of a roller coaster at the top of a 50-meter hill, given 30 m/s at the bottom. (Incorrect calculation in original text, answer is not physically possible from provided data.)
Energy Production and Power Plants
- Energy Sources: Fossil fuels, nuclear, hydroelectric, solar, wind.
- Efficiency: Ratio of useful output energy to input energy. Formula: Efficiency = (Useful Energy Output / Total Energy Input) × 100%
- Power Plants: Convert energy sources into electrical power.
- Fossil Fuels: Burn fuel to produce steam driving turbines.
- Nuclear: Fission reaction creates steam for turbines.
- Renewable: Utilize natural resources (wind, water, sunlight).
- Environmental Impact: Emissions, waste, sustainability aspects.
Example Problems: Power Plants
- Power Plant Efficiency: A plant with 40% efficiency and 100 MJ input. How much useful energy is produced? Answer: 40 MJ
- Wind Turbine Energy Production: A 1.5 MW wind turbine. How much energy is produced in 10 hours? Answer: 15 MWh
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