Balanced and Unbalanced Forces Review Notes PDF

**[Balanced Forces]** **Definition:**\ Balanced forces occur when **two or more forces** acting on an object are **equal in magnitude** but act in **opposite directions**. These forces **cancel each other out**, resulting in **no change** in the object\'s motion. **Key Characteristics:** 1. **Ne...

**[Balanced Forces]** **Definition:**\ Balanced forces occur when **two or more forces** acting on an object are **equal in magnitude** but act in **opposite directions**. These forces **cancel each other out**, resulting in **no change** in the object\'s motion. **Key Characteristics:** 1. **Net Force = 0 N** (Newton) - The forces are equal and opposite, so they cancel out. 2. **No Change in Motion** - If the object is **at rest**, it stays at rest. - If the object is **in motion**, it continues moving at the **same speed and in the same direction**. 3. **No Acceleration** - Since the net force is zero, the object does not accelerate. **Examples of Balanced Forces:** - A book resting on a table: - **Gravity** pulls the book **downward**, and the table applies an **equal upward force** (normal force). - A person standing still on the ground: - The **force of gravity** pulling the person down is balanced by the **ground pushing up**. - A car moving at a **constant speed** on a straight road: - The **engine force** pushing the car forward is balanced by the **friction** and **air resistance** pushing backward. **[Unbalanced Forces]** **Definition:**\ Unbalanced forces occur when the **forces acting on an object** are **not equal** in size or do not act in exactly **opposite directions**. This causes a **net force greater than zero**, resulting in a change in the object\'s motion. **Key Characteristics:** 1. **Net Force ≠ 0 N** - The forces are **unequal** and do not cancel each other out. 2. **Changes in Motion** - The object may **start moving**, **speed up**, **slow down**, or **change direction**. 3. **Acceleration Occurs** - The object accelerates in the direction of the **greater force**. **Examples of Unbalanced Forces:** - **Pushing a Box:** - If you push a box with **60 N** of force to the right and friction resists with **40 N** to the left, the net force is **20 N to the right**. The box will **move to the right**. - **Kicking a Soccer Ball:** - The force from your foot is greater than the resisting forces, causing the ball to **accelerate**. - **A Car Slowing Down:** - When you press the brakes, **friction** between the tires and the road is greater than the forward motion, causing the car to **decelerate**. - **A Falling Object:** - Gravity pulls the object downward. If air resistance is small, the object will **accelerate** towards the ground. **A. DISTANCE** **Definition:**\ Distance is the **total length** of the path an object travels from one point to another, regardless of direction. **Key Characteristics:** - It is a **scalar quantity**, meaning it only has **magnitude** (size) and **no direction**. - It is always a **positive value**. - Measured in **meters (m)** in the SI unit system. **Example:**\ If you walk **3 meters forward** and then **2 meters backward**, the total distance you covered is:\ **3 m + 2 m = 5 m**. **B. DISPLACEMENT** **Definition:**\ Displacement is the **straight-line distance** between the starting point and the ending point, along with the **direction**. **Key Characteristics:** - It is a **vector quantity**, meaning it has both **magnitude** and **direction**. - It can be **positive, negative, or zero** depending on the direction. - Measured in **meters (m)**. **Example:**\ If you walk **3 meters forward** and then **2 meters backward**, your displacement is:\ **3 m - 2 m = 1 m forward**.\ If you return to the starting point, your displacement is **0 meters**. **C. SPEED** **Definition:**\ Speed is the measure of how fast an object is moving, or the **distance traveled** divided by the **time taken**. Formula: Speed = Distance/ Time **Key Characteristics:** - It is a **scalar quantity** (no direction). - Measured in **meters per second (m/s)** or **kilometers per hour (km/h)**. - Speed can be **constant** or **changing**. **Example:**\ If a car travels **100 km** in **2 hours**, its speed is: Solution: Speed = 100 km/ 2 hr = 50 km/hr **D. VELOCITY** **Definition:**\ Velocity is the **speed of an object** in a specific **direction**. **Formula: Velocity = Displacement/ Time** **Key Characteristics:** - It is a **vector quantity** (has both **magnitude** and **direction**). - Measured in **meters per second (m/s)**. - Can be **positive** or **negative** depending on direction. **Example:**\ If a runner moves **100 meters north** in **20 seconds**, the velocity is: Velocity = 100 m, North / 20 seconds = 5m/s , North