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For more information, please see full course syllabus of AP Physics B
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Lecture Comments (9)

1 answer

Last reply by: Jamal Tischler
Tue Aug 18, 2015 7:08 AM

Post by steven horton on June 30, 2014

Thank you Professor Jishi for teaching on educator. You teach the concepts of physics and not the ridiculous numerical problems and examples like other professors.

0 answers

Post by Oguzhan Yabici on March 26, 2013

#1 ... displacement is 2 meters not 20 .

0 answers

Post by Jimmy Wu on September 23, 2012

You mess up at the Extra Example one

0 answers

Post by Riley Argue on April 27, 2012

Thanks professor

0 answers

Post by Shahryar Hussain on March 13, 2012

In "Block pulled Horizontal surface" ,don't we need to know mass also to calculate work done by net Force.

2 answers

Last reply by: Jamal Tischler
Tue Aug 18, 2015 7:42 AM

Post by Kyle Lumague on August 13, 2011

When there is an acceleration on the box equal in both directions, the box will not move to the left, it will stay in place while the truck moves to the right, then the box will just fall after the truck is no longer underneath it.

Work

  • If an object is displaced while some constant force acts on it, the work done by the force is the dot product of the force and displacement vectors.
  • The work done in stretching (or compressing) a spring by a distance x is kx2/2, where k is the force constant of the spring.
  • Work-Kinetic energy theorem: The work done on an object by the net force is equal to the change in kinetic energy:

    Work done by net force = Final kinetic energy – Initial kinetic energy

  • The potential energy of a system is the work done in assembling the system. For an object of mass m at a height h, near the surface of the Earth, the potential energy of the Earth-object system is mgh.
  • If a spring is stretched (or compressed) by a distance x, then the elastic potential energy stored in the spring is kx2/2.
  • Power is the rate of doing work; Power = F.v

Work

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

  1. Work Done by a Constant Force
  2. Stretching or Compressing a Spring
  3. Work Kinetic Energy Theorem
  4. Block Pulled on a Rough Horizontal Surface
  5. Potential Energy of a System
  6. Elastic Potential Energy in a Spring Block System
  7. Power
  8. Extra Example 1: Work Done, Block on Horizontal Surface
    • Extra Example 2: Object and Compressed Spring
      • Extra Example 3: Person Running
        • Work Done by a Constant Force 0:09
          • Example: Force f on Object Moved a Displacement d in Same Direction
          • Force Applied on Object at Angle ø and Displacement d
          • Work Done
          • Force Perpendicular to Displacement (No Work)
          • Example: Lifting an Object from the Surface of Earth to Height h
          • Total Work Done
          • Example: Object on an Inclined Surface
          • Example: Object on Truck
          • Work Done on a Box with No Friction
          • Work Done with Static Friction
        • Stretching or Compressing a Spring 14:50
          • Example: Stretching a Spring
          • Work Done in Stretching a Spring
          • Spring Stretched Amount A
          • Spring Stretched Amount B With Constant Velocity
          • Force at Starting
          • Force at End
          • Total Displacement
          • Average Force
          • Work Done
          • Compressing a Spring
        • Work Kinetic Energy Theorem 24:02
          • Object Mass M on Frictionless Surface
          • Object Moved a Displacement d With Acceleration a
          • Work Done on an Object by Net Force (Kinetic Energy Theorem)
          • Example: Object at Height
          • Force on Object
          • Work Energy Theorem
        • Block Pulled on a Rough Horizontal Surface 35:14
          • Object on a Surface with Friction
          • Coefficient of Kinetic Friction
          • Work Done by Net Force = Change in K.E
          • Applying a Force on an Object at an Angle ø and Displacement d
          • Net Force
          • Work Done
        • Potential Energy of a System 44:39
          • Potential Energy of Two or More Objects
          • Example: Object of Mass m at Height h
          • Earth and Object in Position
          • Potential Energy, u=mgh
          • Absolute Value of Potential Energy
          • Example: Two Objects at Different Heights
        • Elastic Potential Energy in a Spring Block System 52:03
          • Example: Spring of Mass m Stretching
          • Work Done Stretching a Spring
        • Power 55:24
          • Work Done by an Object
          • Rate of Doing Work
        • Extra Example 1: Work Done, Block on Horizontal Surface
        • Extra Example 2: Object and Compressed Spring
        • Extra Example 3: Person Running