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Questions and Answers
What is the definition of work in physics?
What is the definition of work in physics?
- Distance traveled by an object
- Force that causes an object to have a displacement (correct)
- Force applied to an object
- Energy used to lift an object
What is required for work to be done on an object?
What is required for work to be done on an object?
- Only force is required
- Both force and displacement are required (correct)
- Only displacement is required
- Neither force nor displacement is required
What type of energy does an object have when it is moving?
What type of energy does an object have when it is moving?
- Kinetic energy (correct)
- Potential energy
- Electrical energy
- Stored energy
What is the relationship between work and energy?
What is the relationship between work and energy?
What type of energy does an object have due to its position?
What type of energy does an object have due to its position?
What type of energy does a ball possess when placed on the top edge of an incline?
What type of energy does a ball possess when placed on the top edge of an incline?
When is work considered to be done?
When is work considered to be done?
What is the Work-Energy Theorem?
What is the Work-Energy Theorem?
What is the unit of work and energy in the standard metric system?
What is the unit of work and energy in the standard metric system?
What is the correct equation for the Work-Energy Theorem?
What is the correct equation for the Work-Energy Theorem?
What is the total work done as the object moves from point X to point Y?
What is the total work done as the object moves from point X to point Y?
What is the unit of the final answer in the first problem?
What is the unit of the final answer in the first problem?
What happens to the kinetic energy of an object as it moves faster?
What happens to the kinetic energy of an object as it moves faster?
What is the purpose of converting the initial speed from miles per hour to meters per second?
What is the purpose of converting the initial speed from miles per hour to meters per second?
What can be inferred about the kinetic energy of a fast-moving object?
What can be inferred about the kinetic energy of a fast-moving object?
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Study Notes
Work and Energy
- Work is done when a force causes an object to have a displacement, requiring a force, displacement, and cause.
- A force is a push or pull, while a displacement is a distance traveled by an object in a specific direction.
- When a force and displacement are parallel, work is done, and the object has kinetic energy (KE) or energy due to motion.
Kinetic Energy (KE)
- Kinetic energy is the energy due to motion, and an object has kinetic energy when it moves as a result of forces acting on it.
- Examples of kinetic energy include a grocery cart moving down an aisle and a book being lifted from the floor.
Potential Energy (PE)
- Potential energy is the energy due to an object's position, also called stored energy.
- An object has potential energy when it has the potential to do work, such as a ball placed on the top edge of an incline.
- When the ball is released, its potential energy is converted into kinetic energy, and work is done.
Work-Energy Theorem
- The work-energy principle relates the work done by all forces acting on an object to its energy.
- The total amount of work done on an object is equal to the object's change in kinetic energy (final kinetic energy minus initial kinetic energy).
- This principle applies when multiple forces act on an object that changes its state of rest or motion.
Work-Energy Theorem Equation
- The equation for the work-energy theorem is: W = ΔKE, where W is the work done, Δ is the change, and KE is the kinetic energy.
- This equation can be read as "the work done is equal to the change in kinetic energy."
Units of Work and Energy
- The standard metric unit of work and energy is Joule (J), equivalent to one Newton (N) of force, causing a displacement of 1 meter (m).
- One Joule (1 J) is equal to one Newton meter (1 Nm).
- Another non-standard unit is foot-pound (ft.lb.).
Work-Energy Theorem Examples
- A 2-kg object moves from a speed of 3 m/s to 6 m/s, and the total work done is 27 J.
- To stop a 2,000-kg truck moving at 60 mph, 718,240 J of energy is required.
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