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Questions and Answers
What type of energy is associated with an object raised above ground level?
What type of energy is associated with an object raised above ground level?
The formula for calculating kinetic energy is $E_k = 0.5mv^2$.
The formula for calculating kinetic energy is $E_k = 0.5mv^2$.
True
What is the formula for calculating elastic potential energy?
What is the formula for calculating elastic potential energy?
E_e = 0.5ke^2
The energy stored in a stretched spring is known as ______ potential energy.
The energy stored in a stretched spring is known as ______ potential energy.
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Match the following energy types with their equations:
Match the following energy types with their equations:
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What is the formula for calculating gravitational potential energy?
What is the formula for calculating gravitational potential energy?
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The specific heat capacity is defined as the amount of energy required to raise the temperature of one kilogram of a substance by one degree Celsius.
The specific heat capacity is defined as the amount of energy required to raise the temperature of one kilogram of a substance by one degree Celsius.
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What does the variable 'c' represent in the equation for change in thermal energy?
What does the variable 'c' represent in the equation for change in thermal energy?
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Power is defined as the rate at which ______ is transferred.
Power is defined as the rate at which ______ is transferred.
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Match the following terms to their definitions:
Match the following terms to their definitions:
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If a system loses energy during a transfer, what is this process called?
If a system loses energy during a transfer, what is this process called?
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One joule per second is equivalent to a power of 1 kilowatt.
One joule per second is equivalent to a power of 1 kilowatt.
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What is the equation for calculating power?
What is the equation for calculating power?
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The change in thermal energy can be calculated with the formula ΔE = m × c × ______.
The change in thermal energy can be calculated with the formula ΔE = m × c × ______.
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Which of the following methods can reduce unwanted energy transfers?
Which of the following methods can reduce unwanted energy transfers?
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Study Notes
Energy Stores and Changes
- A system is an object or group of objects. Energy storage in a system changes as the system changes.
- Examples include: an object thrown upwards, a moving object hitting an obstacle, a constant force accelerating an object, or a car slowing down.
- Students should describe changes in energy storage in common situations.
- Calculate energy changes due to heating, work by forces, and current flow.
- Calculate how overall energy is redistributed within a system during changes.
Kinetic Energy
- Kinetic energy (Ek) of a moving object is calculated using: Ek = 0.5 × mass × (speed)²
- Ek is in joules (J)
- Mass is in kilograms (kg)
- Speed is in meters per second (m/s)
Elastic Potential Energy
- Elastic potential energy (E) stored in a stretched spring is calculated using: E = 0.5 × spring constant × (extension)²
- E is in joules (J)
- Spring constant (k) is in newtons per meter (N/m)
- Extension (e) is in meters (m)
Gravitational Potential Energy
- Gravitational potential energy (Ep) gained by an object raised above ground level is calculated using: Ep = mass × gravitational field strength (g) × height
- Ep is in joules (J)
- Mass is in kilograms (kg)
- Gravitational field strength (g) is in newtons per kilogram (N/kg).
- Height is in meters (m)
Energy Changes in Systems (Temperature Changes)
- The amount of energy stored in or released from a system as its temperature changes can be calculated using: ΔE = mcΔθ
- ΔE is the change in thermal energy in joules (J)
- m is the mass in kilograms (kg)
- c is the specific heat capacity in joules per kilogram per degree Celsius (J/kg °C)
- Δθ is the temperature change in degrees Celsius (°C)
- Specific heat capacity is the amount of energy to raise the temperature of one kilogram of a substance by one degree Celsius.
Power
- Power is the rate of energy transfer or work done.
- Power (P) = energy transferred / time
- Power (P) = work done / time
- Power is in watts (W)
- Energy/work transferred is in joules (J)
- Time is in seconds (s)
Energy Conservation and Dissipation
- Energy can be transferred, stored, or dissipated, but cannot be created or destroyed
- Only part of the energy is usefully transferred
- The rest is dissipated, stored in less useful ways ("wasted")
- Ways to reduce unwanted energy transfer include lubrication and thermal insulation.
Efficiency
- Energy efficiency is the ratio of useful output energy to total input energy.
- Efficiency = useful output energy transfer / total input energy transfer
- Efficiency = useful power output / total power input
- Units must be consistent
- Efficiency can be expressed as a decimal or a percentage.
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Description
Test your understanding of energy storage and changes within a system. This quiz covers concepts like kinetic and elastic potential energy calculations and their applications in various scenarios. Get ready to dive into energy transformations and redistributions!
