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• ## Discussion

 0 answersPost by Muhammad Khoder on February 19, 2014thank you nice lecture. 0 answersPost by Kajen Kirubahkaran on December 23, 2013gravity is always vertically down and makes an angle "pheta" with the displacement of the object from a to b, so this means that work is done by gravity. Only the normal force is perpendicular to the surface, which means it is perpendicular to the displacement and does zero work on the object. 0 answersPost by Anita Vergis on June 19, 2013I thought that if work was perpendicular to the displacement the work was equal to zero so at the example right before 55:55, I'm confused why we were trying to solve for work? Any insight would be greatly appreciated!

### Work and Energy, Part 1

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.

• Intro 0:00
• Work in One Dimension: Constant Force 0:11
• Particle Moving in X-Axis
• Displacement Δx=x2-x1
• Work Done by the Force W=FΔX
• Example: Object Being Pushed for 10 m (Frictionless case)
• Example: Elevator Descends with constant Velocity
• Work by Tension
• Work in One Dimension: Variable Force 11:28
• Object Displaced from a to b Under Action of Force
• Total Work= F(x1) Δx1
• Special Case : F(x) =F
• Work Done by a Spring 24:30
• Spring Attached to a Object
• Spring Stretched
• Spring Compressed and Released
• Hookes Law
• W=∫F(x) dx ,Initial Position to Final Position
• Work in Three Dimension: Constant Force 41:54
• 3 Components Of 3 Dimensions
• Work Done By F=F.Δx
• Example 48:58
• Object Moves Up and Inclined
• Work Done by Gravity=F.Δr
• W=F.Δr= -mgz
• Work Done By Normal Force=0
• Work in Three Dimension: Variable Force 55:45
• Object Moving From A to B with Time
• W=∫f.dr
• Extra Example 1: Work Done By Force
• Extra Example 2: Mass on Half Ring
• Extra Example 3: Force with Two Paths