1 / 48

Chapter 15

Chapter 15. Simple Machines. Two Types of Work Involved with Using a Machine. Work Input = work that goes in (comes from the force that is applied to the machine) Work Output = work that comes out (force that’s exerted by the machine). Work is Conserved.

stian
Download Presentation

Chapter 15

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. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 15 Simple Machines

  2. Two Types of Work Involved with Using a Machine • Work Input = work that goes in (comes from the force that is applied to the machine)Work Output = work that comes out (force that’s exerted by the machine)

  3. Work is Conserved • can never get out more than you put inin reality, the work output is always less than the work inputWhy? FRICTION

  4. How Much Work isLost to Friction? • Efficiency = work output + f work inputf = energy lost to frictionmachines are more efficient if we keep them clean & lubricated (WO ≈ WI)

  5. Work is ConservedWork = F * d • there can be a change in the forcethere can be a change in the distancenever both at the same time

  6. Forces Involved • Effort force = what a person puts into itResistance force = what you & the machine are working against (often the weight of the object being moved)

  7. Mechanical Advantage • # of times a machine multiples the effort force (what you put in) to overcome the resistance force (usually the weight of the object you’re trying to move)the greater the MA, the easier it is to complete the job

  8. Inclined Plane • alters the way work is done, not the amount of work done • the lower the slant, the longer the distance to push, the lower the effort force needed • the MA increases as the slant of the plane decreases

  9. Wedge • most are made of 2 inclined planes • unlike the inclined plane, the wedge itself moves • as the wedge moves a greater distance, it moves the object with greater force

  10. Wedge • the longer & thinner the wedge, the less effort force required to overcome the resistance • this is why we sharpen blades, knives, etc. – it also increases the MA

  11. Screw • this is an inclined plane wrapped around a cylinder to form a spiral • as the screw rotates, each turn moves the screw up or down a certain distance

  12. Screw • the closer the threads or ridges are, the greater the distance over which the force is multipiled • this means that you may have to work longer to cover that distance, but you will use less effort force

  13. Effort moves farther than resistance • Multiplies effort force & changes its direction

  14. Effort moves farther than resistance • Multiplies effort force but does not change its direction

  15. Resistance moves farther than effort • Does not multiply force • Multiplies the distance the effort force travels

  16. Fixed Pulley • does not multiply force • changes direction of effort force • MA = 1

  17. Movable Pulley • multiplies effort force • cannot changes direction of effort force • MA = effort distance resistance distance

More Related