Ch. 2 - Work and Energy

11% of MCAT Physics content

What is energy?

The property of a system that enables it to do work or cause changes, measured in joules (J).

What is kinetic energy?

Energy associated with an object's movement, dependent on its mass and the square of its speed.

What is potential energy?

Energy stored within a system

ex. gravitational, elastic, electrical, and chemical.

What is gravitational potential energy?

Energy related to an object's mass and its height above a datum (zero-point).

What is elastic potential energy?

Energy stored in a spring, proportional to the spring constant and the square of its stretch/compression.

What is electrical potential energy?

Energy that exists between charged particles.

What is chemical potential energy?

Energy stored in the bonds of compounds.

What is total mechanical energy?

The sum of an object's kinetic and potential energies.

What are conservative forces?

Forces that are path-independent and do not dissipate mechanical energy

ex. gravity, electrostatic forces

What are nonconservative forces?

Forces that are path-dependent and cause energy dissipation

ex. friction, air resistance, viscous drag

What is work?

The process of transferring energy from one system to another, measured in joules (J).

How is work expressed mathematically?

As the dot product of force and displacement: W = F⋅dcos⁡θ

How can work be represented on a pressure–volume curve?

Work is the area under the P–V curve.

What is power?

The rate at which work is done or energy is transferred, measured in watts (W).

What is the work–energy theorem?

The net work done on or by a system equals the change in the system’s kinetic energy.

What is mechanical advantage?

The factor by which a simple machine multiplies the input force to perform work.

What are the six simple machines?

Inclined plane, wedge, wheel and axle, lever, pulley, and screw.

How does mechanical advantage reduce input force?

By increasing the distance over which the input force is applied (assuming 100% efficiency).

What is the load in a simple machine?

The output force, acting over a load distance to determine work output.

What is the effort in a simple machine?

The input force, acting over an effort distance to determine work input.

What is efficiency in simple machines?

The ratio of work output to work input, accounting for nonconservative forces.