| Questions | 5 |
| Topics | Building Loads, Force Lines of Action, Mechanical Advantage, Modulus of Elasticity, Wheel and Axle |
Dead load is the weight of the building and materials, live load is additional weight due to occupancy or use, snow load is the weight of accumulated snow on a structure and wind load is the force of wind pressures against structure surfaces.
Collinear forces act along the same line of action, concurrent forces pass through a common point and coplanar forces act in a common plane.
Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. Such a device utilizes input force and trades off forces against movement to amplify and/or change its direction.
The modulus of elasticity measures how much a material or structure will deflect under stress. Stretch modulus is longitudinal stretch (like stretching raw bread dough), shear modulus is longitudinal deflection (like the horizontal displacement of a stack of magzines when a heavy object is placed upon them), and bulk modulus is compression of volume (like the compression of a loaf of bread under a heavy can at the bottom of a grocery bag).
A wheel and axle uses two different diameter wheels mounted to a connecting axle. Force is applied to the larger wheel and large movements of this wheel result in small movements in the smaller wheel. Because a larger movement distance is being translated to a smaller distance, force is increased with a mechanical advantage equal to the ratio of the diameters of the wheels. An example of a wheel and axle is the steering wheel of a car.