Week 6 – Jss 1 Third Term Basic Science & Technology (BST) Lesson Notes

 WEEK SIX
GRAVITATION AND WEIGHTLESSNESS

• Meaning
  
• Effect
  

 Meaning
GRAVITATION
Gravitation is a force that has effect on the stability of a body.
If an object is tossed up the air, it will full back to the ground because the earth exerts an attraction on it. This attraction is called gravitational attraction.
The gravitational attraction / force between any two object increases as the two objects approach each other.
The earth has a great gravitational full because it has a great mass. The gravitation pull of the earth is always directed to the center.
WEIGHTLESSNESS
Weightlessness is a feeling of being weightless. It does not mean having no weight. As someone move away from the surface of the progressively reduces. In the outer surface of the earth, a person or body has no weight because the gravitational pull of the earth is no longer acting there.
Effect of gravitation on objects

1. Stability of the earth: Gravitation helps every object in the earth include man     to remain stable
2. Weight: The weight of an individual is a measure of the gravitational pull of the earth on that person
3. Revolution of the moon round the earth: The moon is able to revolve round the earth because the gravitational pull of the earth attracts it
4. Balance of planets in our solar system: The sun and all the planets in our solar system exercise gravitational pulls on one another and mutually balance on another in space
5. Work is done against gravity in lifting an object form the earth: Lifting an object from the ground involves opposing gravitational pull, therefore work is done against gravitational attraction of the earth

CLASSWORK 6

1. Define gravitational pull
2. What is weightlessness?

ASSIGNMENT
SECTION A

1. The earth’s gravitational pull on an object is represented by that object’s (a) weight (b) size (c) volume (d) materials
2. The ability of an object to remain stable on earth is due to ______(a) gravitational pull    (b) weightlessness    (c) moon and earth sizes (d) its height
3. Gravitational force is a force of (a) separation (b) attraction     (c) friction (d) opposition
4. The earth has a large gravitational pull on object because the earth (a) has plants and animals (b) is a planet (c) is large in size (d) revolves
5. When a metal ball of 20kg and a wooden ball of 10kg are dropped from the some height
   (a) the metal ball reach the ground before wooden ball    (b) both balls will reach the ground at the same time     (c) the wooden ball falls faster than metal ball (d) the metal ball null full sideways

SECTION B

1. Explain weightlessness
2. State four effects of gravity on an object.