L11: Machines

Which statement best defines a machine?

• Only has one motor

• Makes work easier

• Decreases total amount of work for a job

• Reduces force and distance required for work

Tags

NGSS.MS-ETS1-1

Work Input

• Work done by machine

• Resistance Force

• Applied force

Work Output

• Work done by machine

• Effort Force

• Applied Force

Tags

NGSS.MS-PS3-5

Mechanical Efficiency

• % of Work Output to Input (always less than 100)

• Number of times machine multiples force

• Amount of work done by a machine

• How fast the machine works

A machine is never 100% efficient (2nd Law of Thermodynamics) due to...

• Heat transfers out due to friction

• Humans aren't strong enough (applied force)

• There is not enough renewable energy available

• Machine design needs more technology

Tags

NGSS.MS-PS3-3

NGSS.MS-PS3-4

Mechanical Advantage

• # of times machine multiplies applied force

• Amount of work done

  (force * distance)

• How fast the machine works

• How well machine overcomes friction (ratio of work output to input)

Tags

NGSS.MS-ETS1-2

Mechanical Advantage = 1

• Machine multiples FORCE

• Machine helps

  change DIRECTION

• Machine extends DISTANCE

  of applied force

Mechanical Advantage > 1

(greater than 1)

• Machine multiples FORCE

• Machine helps

  change DIRECTION

• Machine extends DISTANCE

  of applied force

Tags

NGSS.MS-ETS1-1

Mechanical Advantage < 1

(less than 1)

• Machine multiples FORCE

• Machine helps

  change DIRECTION

• Machine extends DISTANCE

  of applied force

What is NOT factored into IDEAL MECHANICAL ADVANTAGE?

• Gravity

• Mass

• Weight

• Friction