Newtons Three Law of Motion and Their Application

Inertial Reference Frames

Is a stationary or Uniformly moving frame of reference

Newton’s First Law of Motion (Law of Inertia)

An object at rest stays at rest and an object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced external force.

Newton’s Second Law of Motion (Law of Acceleration)

The Acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass (F=MA)

Newton’s Third Law of Motion (Action and Reaction)

• For every action, there is an opposite and equal reaction.

• Forces always come in pairs

• They are equal in magnitude but opposite in direction

  Examples

  1. Action: You push down on the ground. Reaction: the group pushes up on you

Philosophiae Naturalis Principia Mathematica

Newton’s Book

Contact Forces

Forces that occur when objects are physically touching

Examples: Friction, Tension, Normal Force

Non-Contact Force

Forces that act at a distance

Examples: Gravity, Magnetic Force

Mass

The amount of matter in an object

• measured in Kilograms (kg)

• Independent of Location

Weight

The force exerted by gravity on an object mass.

• Dependent of Location

• Measured in Newtons

Free-Body Diagrams

Is a visual representation of the forces acting on an object.

Equilibrum

A state where the net force acting on an object is zero

Static Friction

• Force that prevents motion between two surfaces in contact.

• Generally Greater than kinetic Friction

Kinetic Friction

Force that opposes motion when objects are sliding past each other.

Normal Force

The forces perpendicular to the surface supporting an object.

Frictional Force

The force opposing the motion of an object in contact with a surface.

Threshold Angle for Sliding

The angle at which an object begins to slide down an incline

Single-Body Dynamics

Focuses on analyzing the motion and forces acting on a single object.

Multi-Body Dynamics

• Involves the study of systems composed of multiple interconnected bodies.

• Analyzes how forces and motions are transmitted between these bodies, considering their interactions through forces such as tension, compression, and friction.

Tension

• Is a pulling or stretching force that is transmitted along an object such as rope, chain, or rod.

• It is the opposite of compression in terms of force.

Fluid Resistance

Opposes the motion of objects moving through fluids

Air Resistance

Force that resists an object moving through air

Water Resistance

The force that resists an object moving through water.

Drag

Is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid.

Work

• Is done when a force causes a displacement in the direction of the force.

• Is a scalar quantity, meaning it has only magnitude, not direction.

Dot Product

Is a way to multiply two vectors, yielding a scalar

Work done by a varying force

Is the amount of energy transferred to an object when the force applied to it changes in magnitude or direction as the object moves.

Varrying Force

• is applied to an object moving along a straight line.

• X is the position of the object in meters.

Work-Energy Theorem

The work done by a net force on an object is equal to the change in the object’s kinetic energy.

Gravitational Potential Energy

Energy due to an object’s position relative to a reference point.

Elastic Potential Energy

Energy stored in stretched or compressed springs.

Conservative Forces

A force is conservative if the work done by it is independent of the path taken.

Properties:

• Work depends only on the initial and final positions.

• Associated with potential energy.

• No energy is lost as heat or friction

  Examples: Gravitational force and Elastic spring force.

Nonconservative Forces

A force is nonconservative if the work done depends on the path taken.

Properties:

• Energy is dissipated as heat, sound, or other forms.

• Cannot be associated with potential energy.

  Examples: friction and air resistance.

1st Law of Thermodynamics

Also known as conservation of energy. Energy cannot be created or destroyed, it can only change forms.