Week 3 – Jss 1 Third Term Basic Science & Technology (BST) Lesson Notes

WEEK THREE
FORCE

• Meaning
  
• Types of Force
  
• Contact and non-contact force
  
• Magnetic and gravitational force
  

 Meaning
A force can be defined as any action that makes or tries to move, stop or alter the speed of a body in a given direction. Force can also be said to mean a push or a pull. The unit of force is Newton (N). Force is given by the formula:
Force (F) = Mass (m) x Acceleration (a)
F = ma
Types of Force
There are two types of force namely:

1. Contact force
2. Non-contact

Contact and non-contact force

1. CONTACT FORCES: These are forces which sources are in contact with the body to which they are applied. The contact forces could be direct or indirect. Examples of contact forces are: push, pull, tension, friction, upthrust
   
2. NON- CONTACT FORCES: These are forces which the sources do not require contact with the body they are applied. These forces act through a region in space called field. They are therefore also called force fields. Examples include magnetic force, gravitational force and electric force

Magnetic and gravitational force

1. MAGNETIC FORCE: In a bar magnetic, there is North Pole end south pole end. The like poles repel each other while unlike poles attract each other.

Magnets can attract other magnets, iron fillings or any other metallic materials. This phenomenon show that a magnetic force acts over an area around the magnet. Thus a magnetic force is called a field force which acts over an area.

1. GRAVITATIONAL FORCE: The force which the earth attracts all objects to itself is called the force of gravity or gravitational force. This is the reason why objects above the earth fall down to the earth.
2. ELECTRIC FORCE: Electric force field exists between two electric charges. Unlike charges attract each other while like charges repel each other.

CLASSWORK 3

1. What is force? Give the SI unit
2. State two contact force

ASSIGNMENT 3
SECTION A

1. The correct SI unit of force is (a) Joules (b) Watt (c) Newton (d) Metre
   
2. Which of the following statement is false
   (a) a force changes the shape of a body (b) forces may be balanced or unbalanced (c) a force cannot change the direction of a moving body (d) a force changes the speed of object
   
3. The gravitational force can be found (a) on the earth (b) in the moon     (c) around the planets (d) in the galaxy
   
4. The magnetic force is also known as _________(a) pulse ( b) electrical (c) field force (d) gravitational force
   
5. Which of the following is a type of force (a) electrical (b) heat (c) rotating (d) reversible
   

SECTION B

1. Mention three non-contact force that you know
2. State two importance of force
3. State the difference between contact and non-contact force