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# Chapter 13: Statics

Statics is primarily the study of bodies in static equilibrium. There are two conditions necessary for static equilibrium: the net force on a body equals zero and the net torque on a body equals zero. This is why we have waited until after discussing rotations to consider statics. Although any body with a constant velocity (of its center of mass) and a constant angular momentum is in equilibrium, the conditions of static equilibrium are most often applied to bodies that are at rest and not rotating. In many disciplines, especially mechanical engineering, understanding principles of statics is essential. After all, we hope that our buildings, bridges, cranes, etc., always maintain static equilibrium.

# Table of Contents

## Illustrations

- Illustration 13.1: Equilibrium on a Ramp.
- Illustration 13.2: Center of Mass and Gravity.
- Illustration 13.3: The Force and Torque for Equilibrium.
- Illustration 13.4: The Diving Board Problem.

## Explorations

- Exploration 13.1: Balance a Mobile.
- Exploration 13.2: Static Friction on a Horizontal Beam.
- Exploration 13.3: Distributed Load.
- Exploration 13.4: The Stacking of Bricks.

## Problems

- Problem 13.1: Calculate the angle for a box on an inclined plane to tip.
- Problem 13.2: Calculate supporting tensions in a suspended load.
- Problem 13.3: Calculate the normal forces on the front and rear tires of a truck.
- Problem 13.4: Analyze a box pulled by a rope.
- Problem 13.5: Analyze a bicycle wheel suspended on the edge of a curb.
- Problem 13.6: Analyze a beam attached to a wall and wire.
- Problem 13.7: Analyze a system of two rods, each attached to hinges.
- Problem 13.8: Apply equilibrium conditions to a see-saw.
- Problem 13.9: Analyze a pendulum held at some angle in equilibrium.
- Problem 13.10: Calculate reaction forces and torques on a stuck lever.
- Problem 13.11: Determine where the normal force acts on a box on a ramp.
- Problem 13.12: Calculate center of mass.
- Problem 13.13: Determine the mass of the board.