lecture recording on 24 February 2025 at 10.28.43 AM

Impulse and Momentum

• Impulse-Momentum Theorem: The relationship between force, mass and change in velocity.

  • Formula: F × t = m × Δv

  • Example: F = mass (10,000 kg) × change in velocity (Δv = -10 m/s) ÷ time (t = 0.5 s)

  • Note: Simplifying the calculation process may be quicker, but clarity is important in explanations.

• This theorem highlights that impulse (J) is equal to the change in momentum (Δp).

  • Impulse: J = m × Δv where Δv = V_f - V_i

  • Important: Cannot state impulse as just m × v; it is incorrect. Must indicate momentum change.

Exam and Test Preparation

• Refer to posted PDF and sections from an online textbook (OpenStax) on electricity for additional reading.

  • Emphasized: New topic focuses solely on electricity; prior content doesn't directly apply.

• Test Corrections Procedure:

  • Use test correction sheet to type answers digitally.

  • Clearly show work using the equation editor in digital format for legibility.

Introduction to Electricity

• Static Electricity: The build-up of electric charge on surfaces. It's experienced often in dry conditions (like winter).

  • Example: Rubbing tape—creates attraction due to charge transfer when separated.

  • Charge is a fundamental property of matter caused by the presence of electric charges.

• Charges can’t be seen directly—they're evident through their effects (e.g., attraction).

Charge Fundamentals

• Two types of electricity discussed:

  1. Static Electricity: Charges that are not in motion.

     • Example: Static shocks when removing wool blankets.

  2. Current Electricity: Moving charges, essential for electronics.

• Charge is either positive or negative:

  • Positive charge: More protons than electrons.

    • Cannot gain protons; must lose electrons to become positively charged.

  • Negative charge: More electrons than protons.

    • Gains electrons to become negatively charged.

Charge Measurement and Interaction

• Elementary Charge: Smallest unit of charge, represented by 'e'.

  • e = 1.6 × 10⁻¹⁹ Coulombs

  • 1 Coulomb = 6.25 × 10¹⁸ elementary charges.

• Charge is quantized: Only whole numbers of electrons can be transferred, like pennies. No half electrons.

• When an object has a charge of plus 3e, there are 3 more protons than electrons. Converting that to Coulombs involves multiplying by the value of 'e'.

Understanding Charge Transfer

• Charge Transfer: Movement of electrons is the basis of electric charge—cannot transfer protons.

• Adverse conditions like humidity affect static electricity build-up; drier air enhances it.

Lab Work and Assignments

• Lab Due: A project on electric charge can be expected, along with experimentation.

• Equation Editor: Instruction on its use planned to assist in completing tasks digitally.

  • Intended for showing calculations used during tests or lab work.

Summary and Study Tips

• Focus on key concepts of impulse, momentum, electricity, and charge.

• Engage in practical application (lab work) to help internalize theoretical components.

• Review material on static vs. current electricity to grasp the differences and applications.