Topic 3: Position and Motion PDF

Topic 3: Position and Motion Name _________________ Class __________________ Roll Number __________ Study Guide: Position and Motion Key Concepts 1. Position Definition: Position refers to the specific location of an object at a given point in time. Reference Point: A fixed poi...

Topic 3: Position and Motion Name _________________ Class __________________ Roll Number __________ Study Guide: Position and Motion Key Concepts 1. Position Definition: Position refers to the specific location of an object at a given point in time. Reference Point: A fixed point used to define the position of an object. The choice of reference point can affect the description of an object's position. Coordinate System: Often used to define position in space, typically with axes such as x, y (in 2D) or x, y, z (in 3D). 2. Motion Definition: Motion is the change in position of an object over time. Types of Motion: o Linear Motion: Movement in a straight line. o Rotational Motion: Movement around a central point or axis. o Oscillatory Motion: Back-and-forth movement in a regular pattern (e.g., pendulum). o Circular Motion: Movement along a circular path. 3. Equations and Relationships Position o Position in a 1D space can be described using a single coordinate, e.g., 𝑥 o In 2D space, position is described by two coordinates, (𝑥,𝑦) o In 3D space, position is described by three coordinates, (𝑥,𝑦,𝑧) Motion o Distance: Total path length traveled by an object. o Scalar Quantity: Only magnitude, no direction. o Example: If an object moves 5 meters east, then 3 meters west, the total distance is 8 meters. Displacement: Straight-line distance between the initial and final positions of an object, with direction. o Vector Quantity: Has both magnitude and direction. o Example: If an object moves 5 meters east, then 3 meters west, the displacement is 2 meters east. 4. Graphical Representation Position-Time Graph (x-t graph): o Shows how position changes over time. o Slope of the line represents velocity. o A straight horizontal line indicates the object is stationary. o A straight sloped line indicates constant velocity. o A curved line indicates changing velocity (acceleration). Displacement-Time Graph: o Similar to position-time graph but focuses on displacement. หน้า 1 5. Conceptual Understanding Relative Motion o Understanding that motion is always measured relative to a chosen reference point. o Example: A passenger walking inside a moving train has a different motion relative to the train compared to an observer outside the train. Rest and Motion o An object is at rest if its position does not change with respect to a reference point. o An object is in motion if its position changes with respect to a reference point. Study Guide: Position and Motion Key Concepts 1. Speed Definition: Speed is the rate at which an object covers distance. Formula: Speed = Distance/Time Units: Commonly measured in meters per second (m/s), kilometers per hour (km/h), or miles per hour (mph). Types: o Average Speed: Total distance traveled divided by the total time taken. o Instantaneous Speed: Speed of an object at a specific moment in time. 2. Velocity Definition: Velocity is the rate of change of displacement with respect to time and includes direction. Formula: Velocity = Displacement/Time Units: Measured in meters per second (m/s). Vector Quantity: Includes both magnitude and direction. Difference from Speed: Speed is scalar (only magnitude), while velocity is a vector (magnitude and direction) 3. Acceleration Definition: Acceleration is the rate of change of velocity with respect to time. Formula: Acceleration = Δ Velocity/ Time where ΔVelocity = Final Velocity–Initial Velocity Units: Measured in meters per second squared (m/s²). Types: o Positive Acceleration: Increase in velocity. o Negative Acceleration (Deceleration): Decrease in velocity. o Uniform Acceleration: Constant rate of change of velocity. o Non-Uniform Acceleration: Variable rate of change of velocity. หน้า 2 4. Graphical Analysis Velocity-Time Graph: o Slope represents acceleration. o Area under the curve represents displacement. o A horizontal line indicates constant velocity. o A sloped line indicates constant acceleration. Acceleration-Time Graph: o Area under the curve represents change in velocity. o A horizontal line indicates constant acceleration. o A sloped line indicates changing acceleration. Study Guide: Force and Newton’s Law Study Guide: Force and Newton’s Law 1. Force Definition: A force is a push or pull upon an object resulting from its interaction with another object. Units: Measured in Newtons (N), where 1 Newton = 1 kg·m/s². Types of Forces: Contact Forces: Forces that act on objects through physical contact (e.g., friction, tension, normal force). Non-Contact Forces: Forces that act on objects without physical contact (e.g., gravitational force, electromagnetic force). 2. Balanced and Unbalanced Forces Balanced Forces: o Definition: When all the forces acting on an object are equal in magnitude and opposite in direction, resulting in a net force of zero. o Effect: An object with balanced forces acting on it will either remain at rest or continue to move at a constant velocity. o Example: A book resting on a table with gravity pulling it down and the table pushing it up with equal force. Unbalanced Forces: o Definition: When the forces acting on an object do not cancel out, resulting in a net force that is not zero. o Effect: An object with unbalanced forces acting on it will accelerate in the direction of the net force. o Example: Pushing a stationary car where the applied force overcomes friction, causing the car to move. หน้า 3 3. Net Force Definition: The net force is the vector sum of all the forces acting on an object. Calculation: 𝐹net=∑𝐹𝑖 (Sum all of forces) Concepts: o When multiple forces act on an object, they can be combined to find a single net force. o The net force determines the object's acceleration according to Newton's second law. 4. Newton's Laws of Motion Newton's First Law (Law of Inertia): o Statement: An object at rest stays at rest, and an object in motion stays in motion at a constant velocity, unless acted upon by a net external force. Concepts: o Inertia: The tendency of an object to resist changes in its state of motion. o Equilibrium: When the net force acting on an object is zero, the object is in a state of equilibrium. Newton's Second Law (Law of Acceleration): o Statement: The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. o Formula: 𝐹net=𝑚𝑎 o where 𝐹net is the net force, 𝑚 is the mass, and 𝑎 is the acceleration. o Units: Force (N), Mass (kg), Acceleration (m/s²). Newton's Third Law (Action and Reaction): Statement: For every action, there is an equal and opposite reaction. Concepts: o Forces always occur in pairs. o The forces are equal in magnitude and opposite in direction. หน้า 4