Your SlideShare is downloading. ×
Physics chapter 10 and 11
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×

Introducing the official SlideShare app

Stunning, full-screen experience for iPhone and Android

Text the download link to your phone

Standard text messaging rates apply

Physics chapter 10 and 11

942
views

Published on

Ch 10,11 Notes

Ch 10,11 Notes

Published in: Technology, Economy & Finance

0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
942
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
5
Comments
0
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. Chapter 10 Work, Power & Simple Machines
  • 2. Work
    • Work – product of force exerted on an object and the distance the object moves in the direction of the force.
    • W = F (d) Units: N*m = 1 Joule
    • W = F (d) cos θ
  • 3. Power
    • Power – the rate of doing work; rate at which energy is transferred
    • P = W / t Units: J/s = 1 Watt
  • 4. Machines
    • Machines –
    • ease the load by changing the magnitude or direction of a force, but it does not change the work done.
  • 5. 2 Parts of the Machine
    • Effort Force (F e ) - force exerted by you
    • Resistance Force (F r ) - Force exerted by the machine
    • W in = F e (d e )
    • W out = F r (d r )
  • 6. Mechanical Advantage vs. Ideal Mechanical Advantage
    • Mechanical Advantage (MA) is the ratio of resistance force to effort force
    • MA = F r / F e
    • Ideal Mechanical Advantage (IMA)
    • assumes transfer of all energy (No friction)
    • IMA = d e / d r
  • 7. Efficiency of a Machine
    • Efficiency of a machine is the ratio of output work to input work.
    • Efficiency = (W out / W in ) x 100
    • Efficiency = (MA / IMA) x 100
  • 8. 6 Simple Machines
    • Lever
    • Pulley
    • Wheel and Axle
  • 9. Simple machines in the inclined plane family
    • Inclined Plane
    • Wedge
    • Screw
  • 10. 1 st Class Lever
    • The pivot is between the effort and the resistance (load)
    • Ex: Catapult, See-saw
  • 11. 2 nd Class Lever
    • Pivot is on one end and resistance force is in the middle
    • Ex: Wheelbarrow
  • 12. 3 rd Class Lever
    • Pivot is on one end and effort force is in the middle
    • Ex: Broom, Hockey Stick, Shovel
    Load Effort Pivot
  • 13. Chapter 11 Potential and Kinetic Energy
  • 14. Energy
    • Energy – the ability to change an object or its surroundings
    • There are several types of energy, but we will focus on these two.
    • Potential Energy – energy stored in an object because of its position or state
    • PE = mgh
    • Kinetic Energy – energy due to the motion of an object
    • KE = 1/2mv 2
  • 15. Work Energy Theorem
    • The net work done on an object is equal to its change in kinetic energy.
    • Work = ∆KE = KE f – KE i
    • If the net work is positive (Force is in the same direction as motion) then KE increases; if the net work is negative (Force in the opposite direction as motion) then KE decreases.
    • F d = KE f – KE i
  • 16. The Law of Conservation of Energy
    • Within a closed, isolated system energy can change form, but the total amount of energy is constant.
    • KE i + PE i = KE f + PE f
    • Mechanical Energy = KE + PE
  • 17. Energy of a Pendulum
    • Where is the potential energy the greatest?
    • 1 and 5
    • Where is the kinetic energy the greatest?
    • 3
    • If the pendulum has 10 J of kinetic energy at point 3, how much mechanical energy does it have at point 4?
    • 10 J
  • 18. Why is the first hill the highest on a roller coaster?
    • It has to store the most potential energy so it can be converted to kinetic energy to finish the ride.
  • 19. The energy conversions in the pole vault
    • Kinetic on the runway
    • Elastic when the pole bends
    • Potential and Kinetic as he moves off the ground
    • All potential at bar clearance
    • Kinetic as he hits the mat
    • Thermal after the landing
  • 20. Elastic and Inelastic Collisions
    • Perfectly Elastic Collision (Bounces) – A collision where the kinetic energy is conserved
    • Inelastic Collision (Sticks) – A collision where some of the kinetic energy is changed into other forms (usually heat)