AIM: ?

OBJ: Given notes and activity sheet SWBAT with 70% accuracy

DN:

ACT:

HW:

Simple MachinesMachines help by making work (Wi) easier.

To make work easier, you can reduce the input force (Fi) by increasing the input distance (Di) you exert (apply).

There are six (6) basic kinds of simple machines: inclined plane, wedge, screw, lever, wheel & axle, and pulley.

Simple MachinesInclined plane (ramp): flat sloped surface

Wi = decrease Fi x increase Di

MA (ramp) = L (ramp)

H (ramp)

Simple MachinesWedge = two inclined planes (back to back) that can move; produces two output forces (Fo).

MA(wedge) = L

W

Simple MachinesScrew = an inclined plane wrapped around a cylinder.

MA(screw) = thread length

screw length

Simple MachinesLevers = rigid bar that pivots/rotates on a fixed point.

Fulcrum = fixed point that a lever pivots around.

In 1st and 2nd class levers, input force (Fi) can be reduced by increasing input distance (Di).

MA(lever) = Dfulcrum↔Fi

Dfulcrum↔Fo

Simple MachinesTypes of Levers: http://www.enchantedlearning.com/physics/machines/Levers.shtml

First Class Lever: Fo F Fi

change force direction; as fulcrum close to Fo , Fo increases

Example: scissors, pliers, seasaw

Second Class Lever: Fi Fo F

same force direction; as fulcrum close to Fo , Fo increases

Example: doors, nutcracker, bottle opener

Third Class Lever: Fo Fi F

same force direction; as fulcrum close to Fi , Fo decreases

Example: fishing pole, shovel, baseball bat