Newton's Laws of Motion

Newton's Laws of Motion

Essential Questions

  • What is Newton’s first law of motion?

  • What is Newton’s second law of motion?

  • What is Newton’s third law of motion?

  • How can you determine the momentum of an object?

  • What is the law of conservation of momentum?

Force

  • Definition: A push or a pull on an object

  • Effects of Force:
      - Causes a change in the motion of an object
      - Related to mass and acceleration through the formula F=mimesaF = m imes a

  • Unit of Measurement: Force is measured in newtons (N)

Pop Quiz

  • Question: Since friction is a force, what unit is friction measured in?

  • Answer: NEWTONS

Sir Isaac Newton

  • Description:
      - English physicist and mathematician from the 1600s
      - Regarded as one of the most influential scientists of all time

  • Contributions: Formulated the three fundamental laws of motion known as Newton’s Laws of Motion

Newton’s Laws of Motion

1st Law

  • Also known as: The Law of Inertia

  • Definition: An object at rest tends to stay at rest, or an object in motion tends to stay in motion, unless acted on by an unbalanced force.

  • Examples:
      - A book sitting on a table
      - A satellite orbiting Earth
      - A person hitting the windshield during a car crash

2nd Law

  • Also known as: The Law of Force and Acceleration

  • Definition: The acceleration of an object depends on the net force acting on it and the mass of the object, expressed mathematically as F=mimesaF = m imes a.

  • Examples:
      - It takes more force to push a loaded grocery cart than an empty cart
      - A thrown baseball will travel a greater distance than a bowling ball

3rd Law

  • Also known as: The Law of Action/Reaction

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

  • Examples:
      - A rocket taking off
      - Earthquakes caused by tension between tectonic plates
      - You feel the bat “ping” when you make contact with a baseball

Newton's Laws of Motion Table

Newton’s Laws

Examples

Formula

Newton’s First Law

A parachutist jumping from an airplane

Inertia

Newton’s Second Law

Pushing a car versus pushing a truck

F=maF = ma

Newton’s Third Law

Rifle recoil

F1=−F2F_1 = -F_2

Momentum

  • Definition: A measurement of mass in motion, representing how much power is needed to overcome inertia.

  • Formula: Momentum can be calculated using the formula:
      extmomentum=extmassimesextvelocityext{momentum} = ext{mass} imes ext{velocity}

  • Unit of Measurement: Momentum is measured in kilogram-meters per second (kg*m/s)

Law of Conservation of Momentum

  • Definition: The principle that the combined momentum of objects in a system remains constant after a collision.

  • Key Concept: Momentum is conserved in all actions and reactions, including head-on collisions.