Lesson Notes By Weeks and Term - Junior Secondary 1

Gravitation and weightlessness

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TERM – 3RD TERM

WEEK SIX

Class: Junior Secondary School 1

Age: 12 years

Duration: 40 minutes of 5 periods each

Date:

Subject: BASIC SCIENCE

Topic: GRAVITATION AND WEIGHTLESSNESS

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

  1. Explain Gravitation and Weightlessness
  2. Identify the effects of Gravitation on Objects
  3. Demonstrate the effect of gravitational pull on objects

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures,

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

PRESENTATION

TEACHER’S ACTIVITY

STUDENT’S

ACTIVITY

STEP 1

INTRODUCTION

The teacher explains the meaning of Gravitation and Weightlessness to the students.

Students pay

attention

STEP 2

EXPLANATION

Teacher explains the effects of gravitation on objects.

Students pay

attention and

participate

 

STEP 3

DEMONSTRATION

Teacher guide students to demonstrate the effects of gravitational pull on objects.

Students pay

attention and

participate

STEP 4

NOTE TAKING

The teacher writes a summarized

note on the board

The students

copy the note in

their books

 

NOTE

GRAVITATION AND WEIGHTLESSNESS

Gravitation

Gravitation, also known as gravity, is a fundamental force of nature that causes objects with mass to attract each other. It is the force that keeps planets in orbit around stars, moons in orbit around planets, and objects on Earth's surface from floating off into space.

Gravitation explains why objects fall to the ground when dropped and why celestial bodies such as planets and stars exert gravitational pull on each other. The strength of the gravitational force depends on the masses of the objects involved and the distance between them. On Earth, the force of gravity pulls objects toward the center of the planet, giving them weight.

Weightlessness

Weightlessness, also known as microgravity or zero gravity, is the sensation experienced by objects and people when they are in freefall or orbiting in space. Despite the name, weightlessness does not mean the absence of gravity; rather, it occurs when an object is falling freely under the influence of gravity but does not experience any support or resistance.

Effects of Gravitation on Objects

Gravitation, or gravity, has several effects on objects:

  1. Weight: Gravity gives objects weight by pulling them toward the center of a massive body, such as the Earth. The weight of an object is the force with which it is attracted toward the Earth's surface due to gravity. Weight is a measure of the gravitational force acting on an object and is calculated as the mass of the object multiplied by the acceleration due to gravity

  (W = mg).

  1. Acceleration: Gravity causes objects to accelerate toward the center of a massive body. On Earth, this acceleration is approximately 9.8 meters per second squared (m/s²). This means that for every second an object falls, its velocity increases by 9.8 m/s.
  2. Orbital Motion: Gravity governs the motion of celestial bodies such as planets, moons, stars, and galaxies. It keeps planets in orbit around the Sun and moons in orbit around planets.
  3. Tides: Gravity causes the phenomenon of tides on Earth's oceans. The gravitational pull of the Moon and, to a lesser extent, the Sun, creates tidal forces that cause the ocean's water level to rise and fall in predictable patterns.
  4. Shape of Celestial Bodies: Gravity determines the shape of celestial bodies. For example, the Earth is approximately spherical due to the gravitational forces acting equally in all directions, pulling matter toward the center.

Demonstrating the effect of gravitational pull on objects

One way to demonstrate the effect of gravitational pull on objects is by conducting a simple experiment:

Materials Needed:

  1. A small object (such as a ball or a coin)
  2. A tall building or a high platform (with safety precautions in place)
  3. Stopwatch or timer (optional)

Procedure:

  1. Stand at the top of the tall building or platform, ensuring that there is a clear space below and taking necessary safety precautions.
  2. Hold the small object (ball or coin) in your hand, ready to drop it.
  3. Carefully drop the object from the edge of the building or platform, allowing it to fall freely toward the ground.
  4. Observe the motion of the object as it falls.

Observations:

  1. As you drop the object, it accelerates downward due to the force of gravity acting on it.
  2. The object falls straight downward, following a vertical path toward the ground.
  3. The speed of the object increases as it falls, demonstrating the effect of gravity's acceleration.
  4. The object eventually reaches the ground, where it comes to a stop upon impact.

Explanation:

This experiment demonstrates the effect of gravitational pull on objects. Gravity is the force that pulls objects toward the center of the Earth. When the object is dropped, gravity accelerates it downward, causing it to fall toward the ground. The object falls in a straight line because gravity acts vertically downward, pulling the object directly toward the Earth's center. The speed of the falling object increases over time due to the acceleration of gravity until it reaches the ground, where it comes to a stop upon impact.

EVALUATION: 1. Define gravitation.

  1. Mention and explain the effects of gravitation.
  2. What is Weightlessness?

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively