1.1 What is Force?

• A force is a push or pull acting on an object.
  
  

• It can change an object’s motion, speed, direction, or shape.
  
  

• Force is a vector quantity (has both magnitude & direction).
  
  

1.2 Types of Forces

A. Contact Forces (Require physical contact)

• Examples: Pushing a cart, pulling a rope, kicking a ball.
  
  

B. Non-Contact Forces (Act at a distance)

• Gravitational Force (Earth pulls objects down).
  
  

• Magnetic Force (Magnets attract or repel).
  
  

• Electrostatic Force (Charged objects interact).

2.1 How Force Affects Objects

• Starts or stops motion (Kicking a ball).
  
  

• Changes speed (Accelerating a car).
  
  

• Alters direction (Hitting a moving ball).
  
  

• Modifies shape (Squeezing a rubber ball).
  
  

2.2 Balanced vs. Unbalanced Forces

• Balanced Force: No motion occurs (e.g., book on a table).
  
  

• Unbalanced Force: Causes motion (e.g., pushing a toy).

3.1 Friction: A Special Force

• Definition: A force that opposes motion.
  
  

• Examples:
  
  

  • A rolling ball stops due to ground friction.
    
    

  • A car slows down when brakes are applied.
    
    

3.2 Why is Friction Important?

• Pros: Helps us walk, stops vehicles.
  
  

• Cons: Causes wear & tear, reduces efficiency.
  
  

Activity: Ask students, “What would happen if there was no friction?”

3.3 Recap & Quick Quiz

• Summarize key points.
  
  

• Quiz Questions:
  
  

  1. What are the two types of forces?
     
     

  2. How does force change an object’s motion?
     
     

  3. Give one real-life example where friction helps us.

Tossing a ball and recording in slow motion helps visualize motion concepts.

The motion is divided into two parts: upward motion and downward motion for better understanding.

At the highest point, the ball’s velocity is zero, and it gains speed as it falls.

The initial velocity (u), final velocity (v), acceleration (a), time (t), and displacement (s) are key variables in motion equations.

Gravity acts as the force accelerating the ball at 10 m/s² during free fall.

The three equations of motion:

• v = u + at
  
  

• s = ut + ½ at²
  
  

• v² = u² + 2as
  
  

For downward motion, acceleration due to gravity is +10 m/s², while for upward motion, it is -10 m/s².

Using the equations, we can calculate velocity, displacement, and acceleration for different time intervals.

The same principles apply regardless of the object’s mass, as all objects accelerate equally under gravity.

These equations simplify complex motion problems and are essential for solving physics problems efficiently.