Unit+3+Force
Page 1: Course Overview
W PHYS 2130: Physics for the Life Sciences I
Page 2: Unit Overview
UNIT 3: Forces and Newton's Laws
Emphasis on understanding mechanical forces.
Page 3: Topics List
3-1: Principles of motion & net force
Page 4: Principles of Motion
Key Principles for Motion Investigation:
Inertia: Resistance of an object to change in its state of motion.
Mass: Amount of substance in an object.
Interactions: Forces acting between objects.
Egotism: Objects react only to immediate influences on them.
Reciprocity: Interaction forces occur in pairs between objects.
Superposition: Net force is the vector sum of all individual forces.
Page 5: Inertia
Definition: An object at rest remains at rest; an object in motion remains in motion unless acted upon by an external force.
Equivalent Statement: An object maintains its velocity (including zero) without external influence.
Mass: Quantifies the amount of substance.
Page 6: Force Interactions
Forces: Changes in velocity occur through interactions (push/pull).
Contact Forces: Direct physical contact between objects.
Non-contact Forces: Forces acting at a distance without direct contact.
Page 7: Force Vectors
Vectors Model: Forces are represented mathematically as vectors.
Magnitude: Strength of the force.
Direction: Direction of the force.
All forces, whether contact or non-contact, are modeled as vectors.
Page 8: Egotism and Reciprocity
Egotism: Objects respond only to present influences; influences applied to other objects do not affect motion of the influenced object.
Reciprocity: Forces between two interacting objects are equal and opposite, expressed as:( F_{B \to A} = - F_{A \to B} )
Page 9: Superposition of Forces
Net Force: Resultant force acting on an object, calculated as the vector sum of all acting forces.
Condition of equilibrium: If ( F_{net} = 0 ), forces balance with no change in velocity.
Page 10: Vector Addition by Components
Component Addition:
Net force equation ( ( \vec{C} = \vec{A} + \vec{B} ) ) breaks down to separate x and y components.
Ensure proper handling of sign directions in calculations.
Page 11: Net Force by Vector Components
Equations:
( F_{net,x} = F_{1,x} + F_{2,x} + ... )
( F_{net,y} = F_{1,y} + F_{2,y} + ... )
Page 12: Topics Summary
3-2: System diagrams & free body diagrams.
3-3: Impulse
Page 13: System and Free Body Diagrams
Modeling Techniques: Use diagrams to visualize objects and interactions.
Page 14: Free Body Diagram Explanation
Scenario: Two blocks at rest with interactions and contact forces.
Forces acting on blocks include:
Normal forces
Gravitational force
Applied push
Page 15: System Diagrams
Create diagrams for stacked blocks: Illustrate forces acting on and among the blocks.
Page 16: Elements of Free Body Diagrams
Diagram Components:
Coordinate axes
Dot representing the object
Labeled force vectors and net force vector
Page 17: Impulse
Impulse: Represent physical quantities like force and impulse using vectors.
Page 18: Impulse-Momentum Theorem
Impulse Equation: ( I = F \Delta t = m \Delta v )
Cumulative impulse can be graphically determined as area under force-time graph.
Page 19: Additional Topics
3-4: Newton's first law
3-5: Newton's second law
Page 20: Newton's First Law Overview
Application: Use vector representation for forces in an object’s motion evaluation.
Page 21: Statement of Newton's First Law
Objects maintain a constant velocity in the absence of net forces:( \vec{F}_{net} = 0 ) results in ( v = 0 )
Page 22: Balanced Forces
Net Force Definition: Sum of all acting forces.
Separate balance equations for x and y components indicating independent interaction.
Page 23: Newton's Second Law Overview
Quantitative predictions of object behavior using Newton's laws understanding.
Page 24: Newton’s Second Law Formulation
Basic Law: ( F = ma ) (acceleration ratio)
Consistent application in spatial dimensions.
Page 25: More Details on Newton's Second Law
Acceleration and net force session directionality.
Balanced forces leading to constant velocity inertia understanding.
Page 26: Additional Topics
3-6: Newton's third law
Page 27: Concept of Newton’s Third Law
Analysis of forces affecting object in motion using directed interactions.
Page 28: Formal Statement of Newton’s Third Law
Gravity Force Interaction: Action and reaction pairs between two bodies.
Page 29: Newton’s Third Law Application
Equal and opposite forces, emphasizing action/reaction scenarios.
Page 30: Further Topics
3-8: Gravitational force & weight
3-9: Free fall motion
Page 31: Gravitational Force Overview
Explanation of gravity as an attractive force between massive objects.
Utilize gravitational constant and proportional equations.
Page 32: Gravitational Force Interpretation
Demonstrated proportions including distance separation and mass interaction.
Page 33: Free Fall Motion Explanation
Distinguishing conditions for free fall regarding absence of other forces.
Page 34: Characteristics of Free Fall
All objects fall at the same acceleration due to gravity regardless of mass.
Page 35: Weight Definition
Weight Force: Gravitational attraction for an object towards Earth.
Expressed mathematically with weight equation: ( W = mg ).
Page 36: Projectile Motion Nature
Analysis of mixed motion components in free fall context.
Page 37: Rules of Projectile Motion
Independence Principle: X and Y motion directions are separately assessed showcasing acceleration effects.
Page 38: Horizontal and Vertical Components
Assumptions maintaining constant forces in specific motion axes during motion considerations.
Page 39: Projectile Motion Example
Breakdown of example involving velocity components at given time intervals.
Page 40: Displacement Calculation Example
Evaluation of displacement in trajectory during motion intervals.
Page 41: Arrow Landing Calculation Example
Finding landing distance through gravitational time intervals for projectile.
Page 42: Additional Topics
3-10: Spring force & Hooke’s law
3-11: Normal & tension forces
Page 43: Spring Force & Hooke’s Law
Exploring spring mechanics and the concept of restoring forces.
Page 44: Spring Force Overview
Definitions and the mathematical foundation given by Hooke’s law: ( F_{sp} = k \Delta x ).
Page 45: Spring Force Graphs
Relationship between spring constant and linear force application demonstrated.
Page 46: Elastic Limit of Springs
Hooke's law application limitations and non-linear behavior interpretations.
Page 47: Normal Force Analysis
Clarification of the force responsible for maintaining the contact between an object and surface.
Page 48: Overview of Normal Force Characteristics
Interaction and nature of normal force in support and weight relations.
Page 49: Example Problem on Normal Force
Upward normal force reaction against applied downward pressure on a resting object.
Page 50: Class Example on Forces
Comparing magnitudes of forces against gravitational weight establishing equilibrium situations.
Page 51: Additional Topics
3-12: The friction force
3-13: Viscous & drag forces
Page 52: Overview of Friction Force
Understanding friction's nature and its dependency on surfaces interacting.
Page 53: Friction Mechanics
Definition: Friction between sliding surfaces and factors affecting friction coefficients.
Page 54: Friction Types Overview
Kinetic & Static Friction:
Opposing forces based on conditions of motion or rest.
Page 55: Static Friction Dynamics
Static friction only permits motion once a threshold force applies.
Page 56: Friction Types Relationship
Kinetic friction as a constant force contrasting with adaptable static friction.
Page 57: Static Friction Example
Practical example defining static friction from applied forces.
Page 58: Resolving Static Friction Problem
Emphasizing non-movement leading to friction equils applied force illustrations.
Page 59: Viscous and Drag Forces Analysis
Understanding resistive forces based on relative motion through fluids.
Page 60: Overview of Fluid Forces
Distinction between drag and viscous forces corresponding with speed.
Page 61: Viscosity Force Representation
Relation of viscous forces with speed of object through a fluid.
Page 62: Drag Force Definition
Drag as proportional to the square of relative velocity in motion analysis.
Page 63: Understanding Fluid Interaction Forces
Comparison of drag and viscosity focusing on importance in specific scenarios.
Page 64: Resistive Force Graphing Example
Visual representation of various resistive forces demonstrated through graph analysis.
Page 65: Resistive Graph Inquiry
Matching examples of resistive forces to respective graph lines.
Page 66: Additional Topics
3-14: Electric charge
3-15: The electric force
Page 67: Understanding Electric Charge
Predicting distributions of electric charges based on conservation principles.
Page 68: Electricity Impact on Biology
The role of electric interactions at cellular levels and effects on biological molecules.
Page 69: Overview of Electric Force
Fundamental nature of electric charge and force between charged objects.
Page 70: Electric Charge Properties
Charge Intricacies: Positive and negative charge characteristics.
Magnitude defined in specific units.
Page 71: Quantization of Electric Charge
Importance of net charge being quantized and unequal composition effects.
Page 72: Charge Conservation Law
Conservation principle ensuring constant net charge in closed systems.
Page 73: Conductors vs Insulators
Differences in electrical charge movement across various materials.
Page 74: Polarization Phenomenon
Mechanisms of charge separation leading to attraction effects.
Page 75: Electric Force Usability
Evaluating attractive and repulsive forces systematically through object interactions.
Page 76: Magnitude of Electric Force
Coulomb’s Law application details regarding force magnitude between two charged objects.