Newton's Laws of Motion and Universal Gravitation

Grade 10 · Physics

Semester 1 | Period 2 | Week 11

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Subject: Physics

Semester: 1

Period: 2

Week: 11

School Name:

Teacher’s Name:

Subject: Physics

Grade Level: Grade 10

Week & Period: Week 11, Period II

Date:

Sub-topic: Newton’s Laws of Motion and Universal Gravitation

Learning Objectives:
By the end of this lesson, learners should be able to:

  1. State and explain Newton’s three laws of motion.
  2. Solve problems based on each law.
  3. Demonstrate the application of Newton’s laws in daily life.
  4. State and explain Newton’s law of universal gravitation.
  5. Analyze the gravitational force between two objects.

Instructional Materials:

  • Chart of Newton’s laws
  • Dynamics cart and ramp
  • Masses, strings, pulleys
  • Objects of different masses
  • Newton spring scale

Anticipation (Warm-Up):
Ask learners:

  • “Why does a car stop when brakes are applied?”
  • “Why do we jerk backward when a car starts moving suddenly?”

Building Knowledge:

  1. Newton’s First Law (Law of Inertia):
  • A body remains at rest or in uniform motion unless acted upon by a force.
  • Example: A book on a table remains still until pushed.
  1. Newton’s Second Law (Law of Force and Acceleration):
  • F = ma, where F = force, m = mass, a = acceleration
  • Force causes acceleration proportional to the mass.

Example:
A 4 kg mass is accelerated at 3 m/s².
F = ma = 4 × 3 = 12 N

  1. Newton’s Third Law (Action-Reaction):
  • For every action, there is an equal and opposite reaction.
  • Example: When you push a wall, the wall pushes back equally.

Activities for Newton’s Laws:

  • Use cart and pulley to demonstrate F = ma
  • Bounce a ball against the wall to show action-reaction
  • Push two masses of different sizes to observe different accelerations
  1. Newton’s Law of Universal Gravitation:
  • F = G(m₁m₂)/r²
    Where F = gravitational force, m₁ & m₂ = masses, r = distance between centers, G = 6.674 × 10⁻¹¹ Nm²/kg²
  • Gravitational force acts between all masses

Example:
Find the gravitational force between two 10 kg masses separated by 2 m:
F = G(10×10)/2² = (6.674×10⁻¹¹ × 100)/4 = 1.6685×10⁻⁹ N

Activities:

  • Calculate F between Earth and Moon
  • Solve practice problems involving F = ma and gravity
  • Group discussion: real-life examples (e.g., skydiving, rockets)

Assessment:
Oral:

  1. State Newton’s second law of motion.
  2. What is inertia?

Written:

  1. A 5 kg object accelerates at 2 m/s². What force is applied?
  2. Define the law of universal gravitation and write its formula.

Homework:

  1. A force of 15 N is applied to a 3 kg object. Find acceleration.
  2. State all three laws of motion with examples.
  3. What happens to gravitational force if the distance between two masses doubles?

Expanded Notes:

  • Newton’s laws explain most mechanical behavior
  • Universal gravitation explains planetary motion and satellite orbit
  • Emphasis on cause-effect (force leads to motion change)

Differentiation:

  • Visual learners: Charts of forces, diagrams of masses
  • Kinesthetic learners: Cart experiments
  • Support: Use everyday analogies for abstract laws

Teacher’s Reflection:

  • Could learners connect real-life scenarios to the laws?
  • Did they grasp formula-based problems and the law of gravitation?
  • Who needs reinforcement with F = ma or gravitational calculations?