Study Guide Part I - Levers

Levers Overview

• A lever is a bar or rod that pivots on a fulcrum to apply force and lift a load.
• The measure of effort needed and the distance a load moves depend on their positions relative to the fulcrum.

Lever Principles

• The principle of levers states that effort times its distance from the fulcrum equals load times its distance from the fulcrum.

Types of Levers

• First Class Lever: Fulcrum is positioned between the effort and the load, e.g., a balance scale.
• Second Class Lever: Fulcrum is at one end; load is between the effort and the fulcrum, magnifying force while reducing distance moved.
• Third Class Lever: Fulcrum is at one end; effort is between the load and the fulcrum, decreasing force but increasing distance moved.

Examples of Levers

• First Class: Balance scales.
• Second Class: A wheelbarrow (wheel acts as fulcrum); increases force as the load moves closer to the fulcrum.
• Third Class: Body movements, such as lifting weights with arms.

Compound Levers

• A compound lever consists of two levers joined at the fulcrum, seen in tools like scissors and nutcrackers.

Scales and Leverage

• In a Roberval kitchen scale, an object can be placed anywhere without affecting the measurement due to the equal distribution of forces.
• Bathroom scales and platform scales utilize both first and third class levers.

Piano Mechanics

• The complex system of levers in a piano, known as the action, transmits the player's keystrokes to the hammers.
• Dampers cut off sound by dropping onto the piano wire after the hammer strikes it.
• The piano's pedals adjust the sound produced, while the check and repetition lever facilitates hammer action.

Bicycle Brakes

• A brake handle functions as a second class lever, applying brake blocks to the wheel rims to create friction and slow down or stop the bicycle.

Hydraulic Platforms

• The booms in hydraulic platforms act as levers, utilizing hydraulic pressure to move payloads efficiently.