Forces, Simple Machines, and Levers Vocabulary

Vocabulary practice flashcards covering forces, simple machines, mechanical advantage formulas, and classes of levers from the lecture transcript.

Force

A push or pull, or any action that has the ability to change motion.

Weight

A measure of the force exerted by gravity on an object.

Newton (N)

The SI unit of force; the exact amount of force needed to cause a mass of $1\,\text{kg}$ to accelerate by $1\,\text{m/s}^2$.

Simple machine

An unpowered mechanical device, such as a lever, wheel and axle, rope and pulleys, gears, or a ramp.

Input force (effort)

The force applied to a simple machine.

Output force

The force exerted by a simple machine on the load being moved or lifted.

Lever

A simple machine consisting of a rigid bar, a fulcrum, a load, and an effort force.

Fulcrum

The fixed pivot point around which a stiff lever structure rotates.

Input arm

The side of a lever to which the input force is applied.

Output arm

The end of a lever that exerts the output force to move or lift a load.

Work

The product of force and distance, defined mathematically as $\text{Work} = \text{Force}(F) \times \text{Distance}(L)$.

Principle of Work for Levers

The relationship stating work in equals work out, expressed as $F_{\text{effort}} \times L_{\text{effort}} = F_{\text{load}} \times L_{\text{load}}$.

Mechanical Advantage (MA)

The ratio of output force produced by a simple machine to the applied input force.

Mechanical Advantage Formula

Calculated as $MA = \frac{F_o}{F_i}$, where $F_o$ is output force in newtons and $F_i$ is input force in newtons.

Five Basic Simple Machines

Mechanical devices including wheel and axle, rope and pulleys, ramp, gears, and lever.

First-class lever

A lever in which the fulcrum is positioned between the input force and the output force.

Second-class lever

A lever in which the output force (load) is located between the fulcrum and the input force.

Third-class lever

A lever in which the input force (effort) is applied between the fulcrum and the output force.

Mechanical Advantage equal to 1

Occurs when the input arm and output arm are of equal length, resulting in equal input and output forces ($MA = 1$).

Mechanical Advantage greater than 1

Occurs when the input arm is longer than the output arm ($MA > 1$), allowing a simple machine to multiply force.

Mechanical Advantage less than 1

Occurs when the output arm is longer than the input arm ($MA < 1$), resulting in a smaller output force but greater speed and range of motion.

Seesaw

An example of a first-class lever that changes the direction of force and can have an ideal mechanical advantage equal to, greater than, or less than 1.

Wheelbarrow

An example of a second-class lever that always has a mechanical advantage greater than 1 ($MA > 1$) and does not change the direction of force.

Hockey stick

An example of a third-class lever that always has a mechanical advantage less than 1 ($MA < 1$) and does not change the direction of force.

Pliers

A common hand tool given as an example of a first-class lever.

Human biceps and forearm

An example of a third-class lever system in the human body where effort force is applied between the elbow fulcrum and the load.

Direction Change in First-Class Levers

First-class levers always result in a change in the direction of force.

Direction Change in Second and Third-Class Levers

Neither second-class nor third-class levers change the direction of force.

Ropes and Pulleys System

A simple machine system that translates applied input force on a rope to lift heavy loads, such as an elephant, with proper design.

Classes of Levers Diagram

A visual depiction showing the arrangement of effort, load, and fulcrum for Class 1, Class 2, and Class 3 levers.