Work, Power and Simple Machines

Make work easier to do by:

• Increasing the size of an applied force• Changing the direction of an applied force• Changing the distance over which a force acts

There will always be a trade-off!!!

Create three machines to lift the mass in three different ways

Use the following materials:•Ruler•Marker•tape

http://www.pencils.com/sites/default/files/imagecache/product/Color_Rulers.jpg

http://finepointdesign.com/wp-content/uploads/2011/01/DSC05618_markers_web.jpg

http://27.media.tumblr.com/tumblr_lhs14t9rhm1qzur0wo1_400.jpg

http://physics.fau.edu/observatory/Images/100gmass.jpg

Sketch, label, and describe eachdifferent method.

http://cnx.org/content/m23853/latest/ http://www.the-office.com/summerlift/pulleybasics.htm

http://www.g9toengineering.com/resources/simplemachines.htm

http://en.wikipedia.org/wiki/Ferris_wheel http://makeitgo.wikispaces.com/wedges

http://www.schnauzerlover.com/ramp.htm

What goes in…

Input is also called “effort:”-Effort force is the force applied to a machine-Effort distance is the distance across which the effort is applied

What comes out…

http://tech.texasdi.org/simplemachines http://elimeirkaplan.com/blog/?p=608

Output is also called “resistance:”-Resistance force is the force exerted by a machine-Resistance distance is the distance across which the machine applies effort

FULCRUM

LOAD

EFFORT

Fixed point about whichthe lever rotates

The mass beinglifted by a lever

Force used tolift the load

Review: Force is a push or a pull on an object, and is measured in Newtons

is between the effort and the loadFULCRUM…

RESISTANCE DISTANCE…EFFORT DISTANCE…

Explore the relationship between effort force required to lift a load, and the length of the resistance distance.

Resistance Force = ____ N

Use the following materials:•Ruler•Marker•Tape•Spring Scale•100-g mass

Data Collection: - repeat for 3 trials at this fulcrum position for consistency - average the effort needed for this fulcrum position

Trial Fulcrum Position (cm) Resistance Distance(cm) Effort Force (N)

1

2

3

Average

Data Table 1: Effort force measurements for fulcrum positioned at ____ cm

Number of times the input is increased by a machine

distance resistancedistanceeffort

R

E

ddIMA

forceEffort force Resistance

E

R

FFAMA

The mechanical advantage in a “perfect” world; predicted mechanical advantage

The real mechanical advantage that results when the machine is in use

What did you determine, through your experiment, about the relationship

between the (length of the) resistance arm and the effort needed to lift the load?