Machines Lesson 1

Machines

Machines Evolve

Simple Machine

Simple Machines

• Pulley
• Wheel and axle
• Lever
• Inclined plane
• Screw
• Wedge

Which levers will:
Throw farthest
Lift something heavy
Carry something heavy

How can I make the work the same if the effort is less?

Remember W=FxD

Mechanical Advantage
Load Force/Effort Force
Effort Arm/Load Arm
Drive Gear/Follower Gear

Linkages (subsystem) transfer energy from one spot to another
Pedal to wheel

Transmission
A more complex linkage
Engine energy to wheels

Large drive gear & small follower gear = low torque, fast speed

Small drive gear, large follower gear = low speed, big torque

A combination of fixed and movable pulleys is called a block and tackle.

MA = # of support cords

Two or more simple machines (lever, screw, etc) are a compound or complex machine.

Kinetic Energy = moving energy

Potential Energy = stored chemically or gravitationally

Energy cannot be created nor destroyed - it is transformed or transferred.

Efficiency = work done by machine/work done to operate machine x 100%

Friction drops efficiency

Lubrication, design, innovation can boost efficiency

What things are making a cyclist less efficient?

Friction is also useful

TASK

• Find a ride
• Hard and soft inflation. Why would people ride on a soft tire?
• What is the number of wheel rotations with one pedal stroke?
• What do the numbers on the tire say?