AP Physics 1 Unit Plan-Energy

Unit Title: Energy (Work, Energy, and Conservation of Energy)

Duration: 3 weeks

Prerequisite Knowledge:

• Kinematics (motion, velocity, acceleration)
• Newton's Laws of Motion

Unit Objectives:

By the end of this unit, students should be able to:

1. Define and calculate work done by a force.
2. Understand and apply the work-energy theorem.
3. Differentiate between kinetic energy and potential energy.
4. Solve problems involving conservation of mechanical energy.
5. Analyze systems with non-conservative forces (e.g., friction).
6. Interpret energy bar charts and graphs.

Key Concepts:

1. Work

   • Definition: $W=Fd\cos \theta$
   • Positive, negative, and zero work
   • Work done by variable forces (area under the force vs. displacement graph)

2. Kinetic Energy (KE)

   • $KE=\frac{1}{2}m{v}^2$
   • Work-Energy Theorem: $W_{\text{net}}=\mathrm{\Delta }KE$

3. Potential Energy (PE)

   • Gravitational PE: $U_g=mgh$
   • Elastic PE (springs): $U_s=\frac{1}{2}k{x}^2$

4. Conservation of Energy

   • Total mechanical energy: $E_{\text{total}}=KE+PE$
   • Conservation in the absence of non-conservative forces

5. Non-Conservative Forces

   • Work done by friction: $W_{\text{friction}}=-f_{k}d$
   • Energy dissipation (thermal energy, sound, etc.)

6. Power

   • Definition: $P=\frac{W}{t}$ or $P=Fv$

Lesson Breakdown:

Lesson 1: Introduction to Work

• Objective: Define work and calculate it for constant forces.
• Activities:
  • Demonstration: Pulling a block at different angles.
  • Practice: Calculate work for various scenarios.
  • Graphical analysis: Force vs. displacement graphs.
• Homework: Problems on work calculation.

Lesson 2: Kinetic Energy and the Work-Energy Theorem

• Objective: Relate work to changes in kinetic energy.
• Activities:
  • Derive $W_{\text{net}}=\mathrm{\Delta }KE$ using Newton’s laws.
  • Example problems: Car accelerating or decelerating.
  • Lab: Measure work and kinetic energy using a dynamics cart.
• Homework: Problems on work-energy theorem.

Lesson 3: Potential Energy and Conservation of Energy

• Objective: Understand gravitational and elastic potential energy and apply conservation of energy.
• Activities:
  • Derive $U_g=mgh$ and $U_s=\frac{1}{2}k{x}^2$.
  • Energy bar charts: Visualizing energy transformations.
  • Lab: Pendulum or spring-mass system to explore energy conservation.
• Homework: Problems on energy conservation.

Lesson 4: Non-Conservative Forces

• Objective: Analyze systems with friction and energy dissipation.
• Activities:
  • Discuss non-conservative forces and their effects on energy.
  • Example problems: Sliding box with friction.
  • Lab: Measure energy loss due to friction.
• Homework: Problems involving friction and energy loss.

Lesson 5: Power and Efficiency

• Objective: Define power and calculate it in various contexts.
• Activities:
  • Derive $P=Fv$ for constant velocity.
  • Examples: Power output of a car engine.
  • Discuss efficiency in real-world systems.
• Homework: Problems on power and efficiency.

Lesson 6: Review and Practice

• Objective: Consolidate understanding and prepare for assessment.
• Activities:
  • Group problem-solving: Mixed energy problems.
  • AP-style multiple-choice and free-response questions.
  • Review energy bar charts and graphs.

Student Handout:

• Student Handout-AP Physics 1-Energy