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6) External forces
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external forces
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Here are the key terms and definitions extracted from the document: 1. Crime-Scene Reconstruction: A method used to support a likely sequence of events through physical evidence and witness statements. 2. Bloodstain Pattern Analysis (BPA): The study of bloodstains to interpret the events of a crime scene. 3. Impact Angle: The angle at which a blood droplet strikes a surface, determined using the equation:  4. Surface Texture: A key factor in determining bloodstain characteristics, with harder, less porous surfaces resulting in less spatter. 5. Contact/Transfer Stains: Created when a blood-covered object comes into contact with another surface. • Static Transfers: No lateral movement (e.g., handprints, footprints). • Dynamic Transfers: Lateral motion occurs (e.g., swipes and wipes). 6. Swipe Pattern: Bloodstain resulting from the transfer of blood from a blood-bearing surface onto another surface, indicating motion. 7. Spatter Stains: Bloodstains dispersed through the air due to an external force. • Expiration Pattern: Blood projected from the airways. • Gunshot Spatter: Fine forward spatter from an exit wound and back spatter from an entrance wound. • Arterial Spurt: Blood spurting from a damaged artery due to heart pressure. 8. Cast-Off Pattern: Blood flung from a blood-covered object in motion, commonly seen with weapons. 9. Void Pattern: A blank space in bloodstain deposition due to an object or person blocking the spatter. 10. Flow Patterns: Bloodstains created by the flow of blood under gravitational force, which can indicate movement. 11. Pool of Blood: Blood that collects in a level and undisturbed area, which can give clues about timing. 12. Altered Bloodstains: Bloodstains affected by external factors such as insect activity, clotting, diffusion, or cleanup attempts. 13. Documentation Methods: • Grid Method: A grid overlay is placed on the bloodstain pattern for measurement. • Perimeter Ruler Method: Rulers are placed around stains to provide scale in photographs. 14. Area of Convergence: The point on a two-dimensional plane where bloodstains originated. 15. Area of Origin: The three-dimensional space where blood was projected from, determined using string or laser methods
Updated 84d ago
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Motion: The change in an object's position over time. Acceleration: The rate at which an object's velocity changes over time. Free Fall: The motion of an object under the sole influence of gravity. Displacement: The overall change in position of an object from its initial point to its final point. Velocity: The rate at which an object changes its position in a specific direction. Scalar Quantities: Quantities that have only magnitude (size), such as speed or distance. Vector Quantities: Quantities that have both magnitude and direction, such as velocity or displacement. Aristotle's Concepts of Motion: A theory that posited objects have a natural tendency to move towards their designated place in the universe. Heavy objects fall faster. Galileo's Concepts of Motion: All objects, regardless of mass, fall at the same rate in a vacuum. Objects in motion stay in motion unless acted upon by an external force. Vertical Motion: Motion in the up-down direction, primarily influenced by gravity. Horizontal Motion: Motion in the side-to-side direction. Projectile Motion: The curved path of an object moving through the air under the influence of gravity. Uniform Motion: Motion at a constant speed in a straight line. Speed: The rate at which an object covers distance. Momentum: The product of an object's mass and velocity. Impulse: The change in momentum of an object. Collision: An event where two or more objects exert forces on each other for a short period. Elastic Collision: A collision where both momentum and kinetic energy are conserved. Inelastic Collision: A collision where momentum is conserved, but kinetic energy is not. Short Answer Quiz Instructions: Answer the following questions in 2-3 sentences. Distinguish between distance and displacement. Explain why a feather and a ball will fall at the same rate in a vacuum. Describe the difference between speed and velocity. What is acceleration and how does it relate to velocity? How did Galileo’s understanding of motion differ from Aristotle’s? Define momentum and provide its equation. Explain the concept of impulse and its relationship to force. Differentiate between an elastic and an inelastic collision. What is the principle of the conservation of momentum? How does a free-body diagram help in understanding the forces acting on an object? Short Answer Quiz Answer Key Distance is the total length of the path travelled by an object, while displacement is the overall change in position from the starting point to the ending point. Distance is a scalar quantity, while displacement is a vector quantity. In a vacuum, there is no air resistance. Air resistance is a force that opposes the motion of objects through the air. Without air resistance, gravity affects all objects equally, regardless of their mass, causing them to fall at the same rate. Speed is the rate at which an object covers distance, while velocity is the rate at which an object changes its position in a specific direction. Speed is a scalar quantity, while velocity is a vector quantity. Acceleration is the rate of change of velocity over time. It can be a change in speed, direction, or both. If an object is accelerating, its velocity is changing. Aristotle believed that objects had a natural place and that heavier objects fell faster. Galileo argued that all objects fall at the same rate in a vacuum and that objects in motion tend to stay in motion. Momentum is a measure of a moving object's mass and velocity. It quantifies the difficulty of stopping a moving object. The equation for momentum is p = mv, where p represents momentum, m represents mass, and v represents velocity. Impulse is the change in momentum of an object. It is equal to the force applied to an object multiplied by the time over which the force acts (J = Ft). A larger impulse results in a greater change in momentum. In an elastic collision, both momentum and kinetic energy are conserved. In an inelastic collision, momentum is conserved, but kinetic energy is not. In a perfectly inelastic collision, the objects stick together after impact. The principle of conservation of momentum states that the total momentum of a closed system remains constant, meaning momentum is neither created nor destroyed, only transferred between objects within the system. A free-body diagram helps to visualise all the forces acting on an object. It isolates the object and represents all the forces as vectors, making it easier to analyse the net force and predict the object's motion. Essay Questions Explain the concept of projectile motion and discuss the factors that influence the trajectory of a projectile. Compare and contrast Aristotle's and Galileo's concepts of motion, highlighting the key differences in their understanding. Discuss the relationship between position, velocity, and acceleration, using graphs to illustrate their interdependence. Explain the law of conservation of momentum, providing examples of its application in real-world scenarios, such as collisions. Compare and contrast the different types of collisions (elastic, inelastic, and perfectly inelastic) in terms of momentum and kinetic energy conservation. Glossary of Key Terms Acceleration: The rate of change of velocity over time. Air Resistance: A force that opposes the motion of objects through the air. Collision: An interaction between two or more objects where they exert forces on each other. Displacement: The change in position of an object from its initial position to its final position. Distance: The total length of the path travelled by an object. Elastic Collision: A collision where both momentum and kinetic energy are conserved. Free Body Diagram: A diagram that isolates an object and shows all the forces acting on it. Free Fall: Motion under the influence of gravity only. Gravity: A force of attraction between objects with mass. Horizontal Motion: Motion in the side-to-side direction. Impulse: The change in momentum of an object. Inelastic Collision: A collision where momentum is conserved, but kinetic energy is not. Momentum: The product of an object's mass and velocity. Motion: A change in position over time. Projectile Motion: The motion of an object projected into the air at an angle. Scalar Quantity: A quantity that has only magnitude (size). Speed: The rate at which an object covers distance. Uniform Motion: Motion at a constant speed in a straight line. Vector Quantity: A quantity that has both magnitude (size) and direction. Velocity: The rate at which an object changes its position in a specific direction. Vertical Motion: Motion in the up and down direction.
Updated 182d ago
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External forces
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external forces
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