General Science: Machines and Motion

This flashcard set covers the definitions of simple and compound machines, the basics of translational and rotational motion, and key physics quantities and their relationships as presented in the lecture.

Machine

A device that uses force and motion to perform work, changing the magnitude or direction of a force.

Simple Machine

A basic mechanical device that allows work to be performed with less effort.

Lever

A rigid bar used to exert a pressure or sustain a weight by pivoting on its fulcrum.

Wheel and Axle

A wheel fixed to a shaft called an axle; both move together to lift or move an item by rolling.

Pulley

A grooved wheel around which a rope, belt, or chain passes, used to change the direction or magnitude of a force.

Inclined Plane

A flat surface set at an angle or incline, such as a ramp, used to lift objects by pushing or pulling.

Wedge

A moving inclined plane that tapers to a thin edge, used for splitting or tightening by being driven into something.

Screw

An inclined plane wrapped around a cylinder, forming the path and pitch.

Compound Machine

Two or more simple machines working together to make work easier.

Efficiency

A measure of how much of the energy put into a machine becomes useful output, calculated relative to input energy.

Translational Motion

Motion where the center of mass of an object moves from one place to another; also referred to as linear motion.

Rotational Motion

The motion of a body turning about an axis, where each particle moves along a circular path; also referred to as angular motion.

Distance ($d$)

A scalar quantity that refers to the total length of the path traveled between two positions.

Displacement

A vector quantity that refers to an object's overall change in position, or how far out of place it is.

Speed

A scalar quantity referring to the rate at which an object covers distance.

Velocity ($v$)

A vector quantity referring to the rate at which an object changes its position, calculated as $\frac{\text{change in position}}{\text{time}}$.

Acceleration ($a$)

The rate at which velocity changes, calculated as $a = \frac{v_f - v_i}{t}$ with units of $m/s^2$.

Deceleration

Negative acceleration, which can be a decrease in speed or a change in direction.

Torque ($\tau$)

The ability of a force to cause an angular acceleration of an object; the 'twist' factor measured in Newton-meters ($N \times m$).

Lever Arm ($r$)

The distance from the pivot point (fulcrum) to where the force is applied.

Angular Displacement ($\theta$)

The radian value of the angle displaced by an object in circular motion, where 1\text{ rev} = 2\text{\pi} \text{ radians}.

Angular Velocity (\text{\omega})

The rate of change of angular displacement, related to linear velocity by the formula v = r\text{\omega}.

Angular Acceleration (\text{\alpha})

The time rate of change of angular velocity, related to linear acceleration by the formula a = r\text{\alpha}.

Physical Ergonomics

The science of designing environments, products, and systems to fit the people who use them, such as adjusting a tool to fit a person.