Investigation 1 Levers Vocab Lever a lever is

Investigation 1: Levers

Vocab § Lever- a lever is a simple machine that people use to gain a mechanical advantage, such as making work easier § Fulcrum- The point where the lever arm pivots § Lever Arm- A stick or beam free to pivot at a point

§ Load- The mass lifted or the resistance overcome by a lever § Effort- the force needed to move a load or overcome resistance. Measured in Newtons

Content § A lever can make a load easier to lift, it can move loads, and it reduces effort. § The farther the effort is from the fulcrum, the easier it is to lift the load. § The closer the load is to the fulcrum the easier it is to lift the load

Parts of a lever § The four parts of a lever are: lever arm, fulcrum, load, and effort Advantage- a benefit obtained by using a lever (or other simple machine)

Measuring with Spring Scales § Always zero the scales before starting the day’s activity. § Always use the scale right side up, never upside down. § Pull until the lever arm is level, then read the effort. § Stop before the scale goes past 10 N limit.

Two-coordinate graph § Two coordinate graph- shows the relationship between two variables § A two-coordinate graph is helpful for understanding relationships and making predictions. The x-axis on the bottom describes what you changed during the experiment.

Investigation 2 More Leverage

Classes of Levers § § § F L E 1 2 3 § Or FLE- 1 -2 -3 § Levers can be set up in three basic ways. They are called class 1, class 2, and class 3.

§ Class 1 levers- have the fulcrum in the middle and the load and effort on the ends § Class 2 levers- have the load in the middle and the fulcrum and the effort at the ends § Class 3 levers- have the effort in the middle and the fulcrum and the load at the ends

§ The arrows on the load and the effort point in the direction they are pushing or pulling.

Diagram § A diagram is a drawing that describes the relationship of all the parts of a system. § A diagram uses a system of symbols and conventions to communicate information about lever designs.

* § Many common tools use levers: scissors, pliers, bottle openers, hammers, wheelbarrows, and brooms to name a few. § Effort is reduced as the load moves closer to the fulcrum.

Advantages § Class 1 lever- advantage is effort or distance § Class 2 lever- advantage is effort § Class 3 lever- advantage is distance and speed

Levers Investigation 2 Formula

§ Principle of torque § In any lever system the force of the effort and the force of the load are always working in the opposite direction. § Need to know formula! § Force of the load x Distance of the load = Force of the effort x Distance of the effort

Levers Examples § Class 1 Examples- see saw, crowbar, scissors § Class 2 Examples- Wheelbarrow, crab leg cracker, bottle opener § Class 3 Examples- baseball bat, golf club, fishing pole