Podcast
Questions and Answers
What is mechanical work defined as?
What is mechanical work defined as?
- The rate at which energy is transformed.
- The potential energy stored in an object due to its height.
- The ability to transfer energy when a force causes a displacement. (correct)
- The energy an object possesses due to its motion.
Work is a vector quantity, possessing both magnitude and direction.
Work is a vector quantity, possessing both magnitude and direction.
False (B)
What condition between force and displacement results in zero mechanical work being done?
What condition between force and displacement results in zero mechanical work being done?
perpendicular
The unit of work, equivalent to $1 \frac{kg \cdot m^2}{s^2}$, is known as the ______.
The unit of work, equivalent to $1 \frac{kg \cdot m^2}{s^2}$, is known as the ______.
Match the following scenarios to whether mechanical work is done or not done:
Match the following scenarios to whether mechanical work is done or not done:
A force acting on an object causes a displacement. Which component of the force is used to calculate the work done?
A force acting on an object causes a displacement. Which component of the force is used to calculate the work done?
If there is no force acting on an object, no work can be done.
If there is no force acting on an object, no work can be done.
What term describes the rate at which work is done or energy is transferred?
What term describes the rate at which work is done or energy is transferred?
The unit of power, defined as one joule per second (1 J/s) is the ______.
The unit of power, defined as one joule per second (1 J/s) is the ______.
Match each scenario to its respective type of energy:
Match each scenario to its respective type of energy:
Which type of energy is associated with the motion of an object?
Which type of energy is associated with the motion of an object?
Gravitational potential energy depends on the path taken to raise an object to a certain height.
Gravitational potential energy depends on the path taken to raise an object to a certain height.
In the context of mechanical energy, what is meant by a 'reference point' when calculating potential energy?
In the context of mechanical energy, what is meant by a 'reference point' when calculating potential energy?
The energy stored in a spring when it is stretched or compressed is called ______ energy.
The energy stored in a spring when it is stretched or compressed is called ______ energy.
Match the variables to their corresponding representations in the formula for potential energy (Ep = mgh):
Match the variables to their corresponding representations in the formula for potential energy (Ep = mgh):
According to the conservation of mechanical energy, what happens to the total mechanical energy in a closed, isolated system if no non-conservative forces are present?
According to the conservation of mechanical energy, what happens to the total mechanical energy in a closed, isolated system if no non-conservative forces are present?
Friction is a conservative force.
Friction is a conservative force.
When friction is present, how does it affect the total energy of a system?
When friction is present, how does it affect the total energy of a system?
In scenarios where an external force does work on a system, the total energy of the system ______.
In scenarios where an external force does work on a system, the total energy of the system ______.
Match the following forces with whether they are conservative or non-conservative:
Match the following forces with whether they are conservative or non-conservative:
Flashcards
What is work?
What is work?
The ability to transfer energy; work is done when force transfers energy.
When is mechanical work done?
When is mechanical work done?
Mechanical work occurs when a force and displacement are parallel and there is an angle (other than 90°) between them.
When is NO mechanical work done?
When is NO mechanical work done?
No mechanical work is done when force and displacement are perpendicular, or if there is no force/displacement.
Formula for calculating work?
Formula for calculating work?
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What is power?
What is power?
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What is Gravitational Potential Energy?
What is Gravitational Potential Energy?
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What is Kinetic Energy?
What is Kinetic Energy?
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Conservation of Mechanical Energy?
Conservation of Mechanical Energy?
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What is elastic energy?
What is elastic energy?
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Study Notes
- Work, Power, and Energy are interconnected concepts.
Work
- Work is the ability to transfer energy.
- Work is done only when a force transfers energy.
- 'W' is the symbol for work.
- Work is a scalar quantity, having no direction.
- The units of work are Joules (J).
- 1 Joule is equivalent to 1 kg⋅m²/s² or 1 N⋅m
Mechanical Work
- Mechanical work is done when the force and displacement are parallel.
- Mechanical work is also done when there is an angle (other than 90°) between the force and the displacement.
- No mechanical work is done when the force and the displacement are perpendicular.
- No work is done when there is no displacement.
- Formula for calculating work: W = F⋅Δd, where W is work (J), F is force (N), and Δd is displacement (m).
- The force may be a component (e.g., Fgx, Fay, etc.).
- F and Δd must be along the same direction.
Power
- Power is the rate at which energy is transferred otherwise stated as the rate at which work is done.
- 'P' is the symbol for power.
- Power is a scalar quantity having no direction.
- Units of power are Watts (W).
- 1 Watt is equivalent to 1 J/s.
- Formula for calculating power: P = W/Δt, where P is power (W), W is work done (J), and Δt is time (s).
Mechanical Energy
- Mechanical energy is composed of kinetic energy and gravitational potential energy.
Gravitational Potential Energy
- Potential energy is the amount of energy associated with the position (height) of an object with respect to a reference point.
- We can choose "height zero" as a reference point.
- 'Ep' is the symbol for potential energy.
- Potential energy is a scalar quantity.
- Potential energy is measured in Joules (J).
- Formula: Ep = mgh, where m is mass (kg), g is the gravitational constant (9.8 m/s²), and h is height (m) above chosen zero level.
Kinetic Energy
- Kinetic energy is the amount of energy associated with the motion of an object.
- 'Ek' is the symbol for kinetic energy.
- Kinetic energy is a scalar.
- Kinetic energy is measured in Joules (J).
- Formula: Ek = (1/2)mv², where m is mass (kg) and v is velocity (m/s).
Conservation of Mechanical Energy
- In a closed (isolated) system, the total mechanical energy of the system is constant.
- This means no Ff (friction force) and no Fa (applied force).
- Em(initial) = Em(final), which expands to Ep(initial) + Ek(initial) = Ep(final) + Ek(final)
- The 'initial' and' final' moments do not have to be the start and end.
External and Friction Forces
- When there is friction on the system, total energy is still conserved.
- Friction does work to remove energy from the system.
- Formula: Ep(initial) + Ek(initial) - Wf = Ep(final) + Ek(final)
- When a force is applied to a system, it can add energy to the system.
- Formula: Ep(initial) + Ek(initial) + Wa = Ep(final) + Ek(final)
Elastic Energy
- When a spring is stretched or compressed, it stores elastic potential energy.
- When the spring is released, the extremity of the spring moves, transforming the elastic potential energy into kinetic energy.
- 'Ee' is the symbol for elastic energy.
- Energy stored in a spring is a scalar.
- Elastic energy is measured in Joules (J).
- k is the spring constant (N/m)
- x is the change in length from springs equilibrium (m)
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