Notes From December 2nd
Wedge - A modified incline plane
* (Wedge moves, but inclined plane stays in place)
1. Can be used to split or pierce things.
2. Can be used to keep something in place
- 2 Main Types of wedge
- Single wedge
- Double wedge
- Examples
- Fork
- shovels
- axes
- picks
- keystone
- Mechanical advantage = length/thickness of the big end.
Pulley
1. Simple Pulley
- Used to lift or move things in vertical directions.
- Consists of one or more pulley and a belt, or rope, or cable.
2. Conveyor Belt
- Output force is the weight of the object.
- Input force is the force that pulls down on the weight or the cable.
Levers
First Class
- Fulcrum is between the load and the effort (and underneath them)
- Makes it easier to lift a load(if the fulcrum is closer to the load) or make it lift higher and faster (if the fulcrum is closer to the effort)
- Examples
- Oar
- Seesaw
- Mechanical Advantage =distance from the fulcrum to effort / distance from the folcurm to the load
http://www.mca.k12.nf.ca/sm/lever/lever.htm
Second Class
- Fulcrum is on the edge, the load is in the middle, and the effort is on the opposite end of the Fulcrum.
- Example
- Wheel Barrow
- Push ups
- Crow bars
Third Class
- Fulcrum is still on the end, but the effort is in the middle and the load is on the end.
- Applied force must be more than the load.
- Mechanical advantage is that it moves the load faster and higher.
- Examples
- Diving Board
- Arm
Inclined Plane
- Make transporting something easier (you can raise something easier, but you must push it over a large distance)
- Normal forces are always perpendicular to a surface
- Examples
- Wheel chair ramps
- ski jumps
- You can overcome a big resistance by applying a smaller force over a longer distance
Screws
- Mechanical advantage = circumference / pitch
- Pitch is the distance between each thread
Wheel and Axle
- Wheel rotates around a center point (fulcurm)
- A large wheel rotates around a small axle
- Maybe the most important invention …
- Mechanical Advantage = Radius of the Wheel/Radius of the axle
page revision: 14, last edited: 03 Dec 2008 14:56