Q4-Sci-9-Q4wk3-IMPULSE AND MOMENTUM-1

IMPULSE AND MOMENTUM

Overview

• Subject: Science Grade 9

• Quarter: 4, Week 3

Learning Competency

• Main Objective: Relate impulse and momentum to collisions (e.g., vehicular collision).

• Specific Objectives:

  • Knowledge (K): Define impulse and momentum.

  • Skills (S): Solve problems involving impulse and momentum.

  • Application (A): Display knowledge through practical applications.

Definitions

Momentum

• Definition: Latin word meaning "movement" or "inertia in motion".

• Formula: Momentum () = Mass (m) × Velocity (v)

• Units: Newton-seconds (N.s) or kg.m/s.

• Example: An airplane parked has less momentum compared to a car moving at the same speed.

  • Explanation: The airplane is stationary, thus its momentum is zero.

• Important Note: An object at rest has no momentum; all moving objects possess momentum.

Impulse

• Definition: Change in momentum resulting from a force applied over time.

• Formula: Impulse (I) = Change in Momentum (Δ)

Key Concepts

Relationships Between Variables

• Momentum depends on:

  • Mass (kg)

  • Velocity (m/s)

• Important Equation:

  •  = mv (momentum, mass, velocity)

  • Rearranged forms: m = /v and v = /m

Calculating Momentum

• Sample Problem 1:

  • A 2,500 kg bus moving at 25 m/s:

    •  = (2,500 kg)(25 m/s) = 62,500 kg.m/s

Change of Momentum

• Concept: Momentum changes if its velocity and/or mass changes.

• Formula:

  • Change of Momentum (∆) = Applied Force (N) × Time of Contact (s)

Sample Problems

1. Sample Problem 2: Golf ball collision

   • Given: 0.05 kg ball at 60 m/s

   • Impulse (I) = mΔv = (0.05 kg)(60 m/s) = 3 kg.m/s

2. Sample Problem 3: Frictionless mass and force application

   • Initial momentum = 0 kg.m/s

   • Final momentum after applying force: (final) = (50 kg)(3 m/s) = 150 kg.m/s

3. Sample Problem 4: Collision of trucks

   • Given:

     • Truck 1 (m1): 21,000 kg, v1(initial): 5 m/s, v2(initial): 0 m/s

     • Final velocity after collision: 3 m/s

   • Solve for mass of truck 2 using conservation of momentum.

Law of Conservation of Momentum

• Statement: "In the absence of an external force, the momentum of a system remains unchanged."

• Example: Two skateboarding children pushing off each other with equal and opposite forces.

• Formula:

  • Total initial momentum = Total final momentum

  • m1v1(initial) + m2v2(initial) = m1v1(final) + m2v2(final)

Practice Activities

• Activity 5: Two skateboarders push apart from each other. Calculate the velocity of the heavier skateboarder given the lighter skateboarder moves 3.2 m/s.

True or False Evaluation

• Key Statements to Consider:

  • Standard unit of momentum

  • Relation of mass to momentum

  • Conditions where momentum can change

  • Characterization of momentum as a vector quantity

References

1. Department of Education (2014). Science 9 Learner’s Module.

2. Project EASE Modules.

3. Science Notes

4. The Physics Classroom (2020). Momentum and its Conservation.

5. Exercises and Experiments in Physics.

This structured format will help guide the study of impulse and momentum effectively.