Download Force 4-3 Notes

Sci. 4-3
Types of Machines
Pages 98- 105
A. All machines are constructed
from 6 simple machines: lever,
inclined plane, wedge, screw, wheel
and axle, and pulley.
B. Lever- a bar that pivots at a
fixed point called a fulcrum
st
1)1
class lever- the fulcrum is
between the input force and the
load. ( changes direction of force)
examples: seesaw, hammer pulling
nail
2) 2nd class lever- the load is
between the fulcrum and the input
force.
Examples: wheel barrow,
screwdriver on paint can
rd
3
3)
class lever- the input force is
between the fulcrum and the load
example- hammer striking nail
C.Inclined Plane- a straight slanted surface. A
smaller input force is used over a longer
distance.
1) mechanical advantage of an inclined plane is
calculated by dividing length by height
D.Wedge- a double inclined plane that
moves (doorstops, plows, axe heads, &
chisels)
1)mechanical advantage of a wedge is
length / thickness
E. Screws- an inclined plane that is
wrapped in spirals. (lids, bolts)
F. Wheel and Axle- 2 circular objects of
different sizes.
(Doorknobs, wrenches, ferris wheels,
screwdrivers, steering wheel)
G. Pulleys- grooved wheel that
holds a rope or cable
1) Fixed pulleys- change the
direction of the force
2) Movable pulleys- attached to
object (load) being moved. (does
not change the directions of the
force)
3) Block and tackles- fixed pulley
and movable pulleys used together
H. Compound Machine- a machine
that is made of two or more simple
machines