# Physics in Context - 2nd Edition

## Chapter 2: Work

Some links are repeated for use with more than one lesson.

### 2.1 Work in Mechanical Systems

How Does a Block and Tackle Work?
http://www.howstuffworks.com/pulley.htm
This page describes how a block and tackle allows you to multiply force.

Introduction to Torque, Work, and Power
http://www.renthal.com/shop/support/tech-support/gearing-further
This page describes the relationships among torque, work, and power and their application to the gearing of motorcycles.

http://www.racquetresearch.com/
When you go to this site, check out the article "Introduction to Racquet Science," particularly the section on torque, to find out about the physics involved with tennis racquet performance and tennis injuries.

Calibrating a Torque Wrench
http://www.wikihow.com/Calibrate-a-Torque-Wrench
Illustrated step-by-step instructions for calibrating a click-type torque wrench.

### 2.2 Work in Fluid Systems

How a Tire Pressure Gauge Works
http://www.howstuffworks.com/pressure-gauge.htm
This site describes how a tire pressure gauge works.

How Hydraulic Machines Work
http://www.howstuffworks.com/hydraulic.htm
This site explains the principles behind hydraulic machines from log splitters to heavy equipment.

Inside a Bottle Jack
http://www.hyjacks.net/animation.htm
This page includes an animated graphic that shows how a bottle jack works.

Lifting Salt Water
This page has a video demonstrates the work (and power) calculations for pumping salt water. (Hint: click the "full-screen" button.)

### 2.3 Work in Electrical Systems

Ampere's Biography
http://www-history.mcs.st-and.ac.uk/Biographies/Ampere.html