L15 Energy: Interactions & Potential

Key Announcement: MS1 is Tomorrow at 8am in computer room

Worked Problem

Similar to Knight vs 4 question 9.59. A horizontal spring (k=250 N/m) is compressed 12 cm and a 250g box is placed at the end of the spring. If the coefficient of kinetic friction between the box and the floor is (fk=0.10), What is the box's maximum speed? (Solve 2 ways...)
Question: Why would this be a difficult problem for Newton's approach?
Energy Skate Park: Basics
Potential, Thermal, Kinetic Energy
Click to Run

Key Ideas

ΔEsys = ΔK + ΔU + ΔEth = W + Q

F(s) = - dU/ds

Forces: conservative vs non-conservative

Thinking Steps

  1. Picture
  2. Choose System/Environment
  3. FBD if needed.
  4. Solve noting energy

PPT (Ref: Knight Ch 10)

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