Chapter 9 simple machines
This presentation is the property of its rightful owner.
Sponsored Links
1 / 20

Chapter 9 - Simple Machines PowerPoint PPT Presentation


  • 55 Views
  • Uploaded on
  • Presentation posted in: General

Chapter 9 - Simple Machines. 9.2 Mechanical Advantage pp. 210-216. 9.2 Mechanical advantage. Mechanical advantage is the ratio of output force to input force. 9.2 Mechanical advantage. Machines multiply forces.

Download Presentation

Chapter 9 - Simple Machines

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Chapter 9 simple machines

Chapter 9 - Simple Machines

9.2 Mechanical Advantage

pp. 210-216


9 2 mechanical advantage

9.2 Mechanical advantage

  • Mechanical advantageis the ratio of output force to input force.


9 2 mechanical advantage1

9.2 Mechanical advantage

  • Machines multiply forces.

  • One person could lift an elephant—quite a heavy load—with a properly designed system of ropes and pulleys!


9 1 mechanical advantage

9.1 Mechanical Advantage

Output force (N)

MA = Fo

Fi

mechanical

advantage

Input force (N)


9 2 the lever

9.2 The Lever

  • A lever includes a stiff structure (the lever) that rotates around a fixed point called the fulcrum.


9 2 the lever1

9.2 The Lever

  • Levers are useful because you can arrange the fulcrum and the input arm and output arm to adjust the mechanical advantage of the lever.


9 2 the lever2

9.2 The Lever

  • Each class of levers is defined by the location of the input and output forces relative to the fulcrum.


9 2 gears

9.2 Gears

  • Many machines require that rotating motion be transmitted from one place to another.

  • Gears change force and speed.


9 2 designing gear machines

9.2 Designing Gear Machines

  • The gear ratio is the ratio of output turns to input turns.

  • You can predict how force and speed are affected when gears turn by knowing the number of teeth for each gear.


9 2 gear ratios

9.2 Gear Ratios

Number of teeth

on input gear

To=Ni

Ti No

Turns of output gear

Turns of input gear

Number of teeth

on output gear


9 2 tension

9.2 Tension

  • Ropes and strings carry tensionforces along their length.

  • If the rope is not moving, its tension is equal to the force pulling on each end.


9 2 ramps

9.2 Ramps

  • A ramp is a simple machine that allows you to raise a heavy object with less force than you would need to lift it straight up.

  • The mechanical advantage of a ramp is the ramp length divided by the height of the ramp.


9 2 screws

9.2 Screws

  • A screwis a rotating ramp.

  • You find the mechanical advantage of a screw by dividing its circumference by the lead.


9 2 screws1

9.2 Screws

  • A wedgeis like a ramp that can work while in motion (a ramp is always stationary).

  • A wedge has a side that slopes down to a thin edge.

  • The mechanical advantage for a wedge is inversely related to the size of the wedge angle.


9 2 wheel and axle

9.2 Wheel and axle

  • A wheel rotates around a rod called an axle.

  • The mechanical advantage is the ratio of the radius of the wheel to the radius of the axle.

  • The wheel and axle move together to move or lift loads.


Solving problems

Solving Problems

  • A crowbar is a type of lever that you use to pull a nail out of a piece of wood.

  • If the handle of a crowbar is 40 centimeters and the foot is 2 centimeters, what is its mechanical advantage?


Solving problems1

Solving Problems

  • Looking for:

    • …mechanical advantage of lever

  • Given

    • …input arm = 40 cm; output arm = 2 cm

  • Relationships:

    • M.A. = Length of input arm

      Length of output arm

  • Solution

    • M.A. = 40 cm ÷ 2 cm = 20


Mechanical advantage

MECHANICAL ADVANTAGE

  • Complete “Your Turn” problems on p. 215

  • Complete Skill Sheet


  • Login