(10405) AP Physics 1 Lesson on Impulse and Momentum

Momentum

• Definition: Momentum = mass × velocity.

• Characteristics:

  • Considered "mass in motion".

  • Vector quantity (has direction): same direction as velocity.

  • Units: kilograms × meters/second (kg·m/s).

• Importance:

  • Objects with mass possess inertia and momentum.

  • Example: A moving freight train has significant momentum despite low velocity. Conversely, a small object traveling fast (like space dust) can also possess high momentum.

Impulse

• Definition: Impulse is the product of force and the time duration that force is applied.

• Relation to Momentum: Impulse causes changes in momentum, consistent with Newton's laws.

• Example: In a racquetball scenario, the force applied changes the ball's velocity over time (force~time graph).

• Impulse can be visualized as a force applied during an interaction (e.g., hitting a ball).

Impulse-Momentum Theorem

• An impulse results in a change in momentum:

  • Formula: Impulse = Change in momentum.

• Can be expressed as:

  • Impulse = Force × time.

• The area under the force-time graph represents the impulse.

  • This theorem highlights how forces over time impact the velocity of an object.

Applications and Examples

• Forces can lead to diverse impulse changes, affecting velocities differently based on how forces are applied (sharp vs. gradual).

• Calculating Impulse:

  • Examples with specific values to illustrate losses and changes in velocity due to impulses.

• Real-world instance: A baseball with an initial speed that rebounds with a greater speed, showcasing the change in momentum due to an impulse applied from a bat.

Key Takeaways

• Impulse leads to changes in momentum, reinforcing how forces act over time.

• Momentum consists of mass in motion, encapsulating the essence of an object's inertia and velocity.