Investigation 1: Investigation 1: LeversLevers

VocabVocab Lever- a lever is a simple machine that Lever- a lever is a simple machine that

people use to gain a mechanical people use to gain a mechanical advantage, such as making work easieradvantage, such as making work easier

Fulcrum- The point where the lever arm Fulcrum- The point where the lever arm pivotspivots

Lever Arm- A stick or beam free to pivot Lever Arm- A stick or beam free to pivot at a pointat a point

Load- The mass lifted or the resistance Load- The mass lifted or the resistance overcome by a lever overcome by a lever

Effort- the force needed to move a load Effort- the force needed to move a load or overcome resistance. Measured in or overcome resistance. Measured in NewtonsNewtons

ContentContent A lever can make a load easier to lift, it A lever can make a load easier to lift, it

can move loads, and it reduces effort. can move loads, and it reduces effort. The farther the effort is from the fulcrum, The farther the effort is from the fulcrum,

the easier it is to lift the load. the easier it is to lift the load. The closer the load is to the fulcrum the The closer the load is to the fulcrum the

easier it is to lift the loadeasier it is to lift the load

Parts of a leverParts of a lever The four parts of a lever are:The four parts of a lever are:

lever arm, fulcrum, load, and effortlever arm, fulcrum, load, and effort

Measuring with Spring Measuring with Spring ScalesScales

Always zero the scales before starting the Always zero the scales before starting the day’s activity. day’s activity.

Always use the scale right side up, never Always use the scale right side up, never upside down. upside down.

Pull until the lever arm is level, then read Pull until the lever arm is level, then read the effort. the effort.

Stop before the scale goes past 10 N limit.Stop before the scale goes past 10 N limit.

Two-coordinate graphTwo-coordinate graph Two coordinate graph- shows the Two coordinate graph- shows the

relationship between two variablesrelationship between two variables A two-coordinate graph is helpful for A two-coordinate graph is helpful for

understanding relationships and making understanding relationships and making predictions. The x-axis on the bottom predictions. The x-axis on the bottom describes what you changed during the describes what you changed during the experiment. experiment.

AdvantageAdvantage Advantage- a benefit obtained by using a Advantage- a benefit obtained by using a

lever (or other simple machine)lever (or other simple machine)

Investigation 2 Investigation 2 More LeverageMore Leverage

Classes of LeversClasses of Levers FF 11 LL 22 EE 33

Or FLE- 1-2-3Or FLE- 1-2-3 Levers can be set up in three basic ways. Levers can be set up in three basic ways.

They are called class 1, class 2, and They are called class 1, class 2, and class 3. class 3.

Class 1 levers- Class 1 levers- have the fulcrum in the middle have the fulcrum in the middle and the load and effort on the ends and the load and effort on the ends

Class 2 Class 2 levers- have the load in the middle and levers- have the load in the middle and the fulcrum and the effort at the ends the fulcrum and the effort at the ends

Class 3 Class 3 levers- have the effort in the middle levers- have the effort in the middle and the fulcrum and the load at the ends and the fulcrum and the load at the ends

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

DiagramDiagram A diagram is a drawing that describes the A diagram is a drawing that describes the

relationship of all the parts of a system. relationship of all the parts of a system. A diagram uses a system of symbols and A diagram uses a system of symbols and

conventions to communicate information conventions to communicate information about lever designs. about lever designs.

** Many common tools use levers: scissors, Many common tools use levers: scissors,

pliers, bottle openers, hammers, pliers, bottle openers, hammers, wheelbarrows, and brooms to name a wheelbarrows, and brooms to name a few. few.

Effort is reduced as the load moves Effort is reduced as the load moves closer to the fulcrum. closer to the fulcrum.

AdvantagesAdvantages Class 1 lever- advantage is effort or Class 1 lever- advantage is effort or

distancedistance Class 2 lever- advantage is effortClass 2 lever- advantage is effort Class 3 lever- advantage is distance and Class 3 lever- advantage is distance and

speed speed

Levers Levers Investigation 2 Investigation 2 FormulaFormula

Principle of torquePrinciple of torque In any lever system the force of the effort In any lever system the force of the effort

and the force of the load are always and the force of the load are always working in the opposite direction. working in the opposite direction.

Need to know formula!Need to know formula! Force of the load x Distance of the load = Force of the load x Distance of the load =

Force of the effort x Distance of the effortForce of the effort x Distance of the effort