Challenge 17
Summary
Wedge
Pushes material apart, cuts
Wheel
and Axle
Makes it easy to move things
by rolling them, and reducing friction
Lever
Helps lift heavy weights
using longer distances
Inclined
Plane
Makes it easier to move objects upward;
a longer path, but easier lifting
Screw
Turns rotation into lengthwise movement
Pulley
Makes lifting heavy weights easier
by redirecting force
Complex Machines
• Combining two or more simple machines to
work together
• Examples:
– Car jack combines wedge and screw
– Crane or tow truck combines lever and pulley
– Wheel barrow combines wheel and axle
with a lever
Compound Machines
• Compound machines consist of two or more
simple machines put together.
• Most devices are compound machines.
• They can do more difficult jobs because their
mechanical advantage is greater.
Name the Simple Machines
Present in Each Compound Machine
Compound Machines
COMPOUND MACHINES
• A compound
machine is a
combination of
two or more
simple machines
that operate
together.
COMPOUND MACHINES
• Many familiar compound
machines, such as a car,
a washing machine, or a
clock, are combinations
of hundreds or
thousands of simple
machines.
Compound Machine
Corkscrew
•
•
•
•
•
Inclined Plane
Wedge
Screw
Lever
Wheel and Axle
Compound Machine
Jack
•
•
•
•
Inclined Plane
Wedge
Screw
Lever
A Wedge in a Compound Machine:
Stapler
• Staples are
wedges: they cut
through paper
because their
ends are pointed
in a wedge shape.
• Simple machines
in a stapler:
– Wedge
– Lever
A Wedge in a Compound Machine:
Scissors
• The cutting edge
of scissors is a
wedge.
• Simple machines
in a pair of scissors:
– Wedge
– Lever