Work, Energy and Power

What is the scientific definition of work?

Work is defined as the product of force and displacement in the direction of that force, expressed as W = F × d × cos(θ).

What must occur for work to be done?

Both a force must be exerted and there must be displacement in the direction of the force.

How is net work defined?

Net work (W_net) is the sum of work done by all forces acting on an object.

What does the Work-Energy Theorem state?

The net work done on a system equals the change in its kinetic energy (W_net = Δ KE).

What is kinetic energy?

Kinetic energy (KE) is the energy of motion, given by KE = 1/2 mv².

What is gravitational potential energy?

Gravitational potential energy (PEg) is defined as PEg = mgh, where m is mass, g is gravitational acceleration, and h is height.

What defines a conservative force?

A conservative force is one for which the work done depends only on the initial and final positions, not the path taken.

What is the potential energy stored in a spring?

The potential energy in a spring (PEs) is defined as PEs = 1/2 kx².

What does the conservation of mechanical energy principle state?

The total mechanical energy (KE + PE) of a system remains constant when only conservative forces act.

What does the Law of Conservation of Energy state?

Total energy is constant in any process, undergoing transformations or transfers but never being created or destroyed.

What is the equation representing the conservation of energy?

KEi + PEi + Wnc + OEi = KEf + PEf + OE_f.

What is efficiency in the context of energy?

Efficiency is a measure of useful energy output compared to total energy input, expressed as Eff = useful energy output / total energy input.

How is power defined in physics?

Power (P) is the rate at which work is done or energy is expended, given by P = W / t.

What is the SI unit for power?

The SI unit for power is the watt (W), where 1 W = 1 J/s.

How is energy consumed calculated?

Energy consumed can be calculated as E = Pt, often measured in kilowatt-hours (kW·h) for electrical consumption.

What is the formula for rotational work?

The rotational work done is given by W_net = (net τ)θ, where net τ is the net torque and θ is the angular displacement.

What does θ represent in the work formula?

θ represents the angle between the force and displacement vectors.

What is the relationship between work and kinetic energy?

The net work done on a system results in a change in kinetic energy.

What are nonconservative forces?

Nonconservative forces are forces that do work where the amount of work depends on the path taken.

What happens to gravitational potential energy when an object is lifted?

Lifting an object results in an increase in gravitational potential energy due to its height.

What is the formula for kinetic energy?

Kinetic energy is given by KE = (1/2)mv².

What does the symbol 'm' refer to in the kinetic energy formula?

In the kinetic energy formula, 'm' refers to the mass of the object.

What happens to total mechanical energy when only conservative forces act?

The total mechanical energy remains constant.

How is work done against gravity calculated?

Work done against gravity is equal to the gravitational potential energy change, calculated as W = mgh.

What does 'Eff' stand for in energy equations?

Eff stands for efficiency.

What is the formula for calculating efficiency?

Efficiency is calculated as Eff = useful energy output / total energy input.

What does the term 'net torque' refer to?

Net torque refers to the total torque acting on an object, which causes rotational motion.

What is the relationship between work and power?

Power is the rate at which work is done; therefore, P = W/t.

What unit is used to measure energy in electrical contexts?

Energy is often measured in kilowatt-hours (kW·h) in electrical contexts.

What can be said about energy during transformations?

Energy undergoes transformations or transfers but is never created or destroyed.

What is the formula for potential energy due to a spring?

Potential energy in a spring is given by PE*s = (1/2)kx².

What does the variable 'k' represent in the spring potential energy formula?

In the spring potential energy formula, 'k' represents the spring constant.

What describes the relationship between force and displacement in work?

For work to be done, force and displacement must be in the same direction.

What does 'W' represent in the context of work?

'W' represents the work done on or by a system.

How is the efficiency of an energy process generally expressed?

Efficiency is expressed as a percentage of useful energy output divided by total energy input.

What does the term 'gravitational potential energy' indicate?

It indicates energy stored in an object due to its height in a gravitational field.

What occurs when the work done by nonconservative forces is included in the conservation of energy equation?

The equation accounts for energy losses due to friction or other nonconservative forces affecting the system.

What is the effect of nonconservative forces on mechanical energy?

Nonconservative forces can decrease the total mechanical energy of a system.

What is the significance of the angle θ in the work equation?

The angle θ determines how effective the force is in causing displacement, affecting the amount of work done.

What does 'W_nc' represent in the conservation of energy equation?

W_nc represents the work done by nonconservative forces.

How can you increase the power output of a system?

By increasing the work done in a shorter amount of time.

What happens to kinetic energy when work is done on a system?

The kinetic energy of the system increases if positive work is done.