newton's laws of motion

• What do we mean by inertia?

  The tendency of an object to remain in a steady state
• What does Newton's First Law state?

  The velocity changes only if a resultant force acts
• What is the resultant force on a stationary object?

  Zero
• What is the resultant force on an object moving at a steady speed in a straight line?

  Zero
• What will an object experience if the resultant force on it is not zero?

  Acceleration/change in velocity
• What is the name of the tendency of an object to remain in a steady state at rest or moving in a straight line at a constant speed?

  Inertia
• What forces are balanced when an object travels at a steady speed?

  Resistive forces = driving force
• According to Newton's Second Law, what is the acceleration of an object proportional to?

  The force acting on it
• According to Newton's Second Law, what is the acceleration of an object inversely proportional to?

  Mass
• What is the inertial mass of an object?

  How difficult it is to change its velocity
• What does Newton's Third Law state?

  When two objects interact, they exert equal and opposite forces
• What physical processes are described by starting to move, stopping moving, speeding up, slowing down, and changing directions?

  Acceleration/change in velocity
• What is the tendency of an object to remain in a steady state called?

  Inertia
• What does Newton's First Law state about an object's velocity?

  It changes only if a resultant force acts
• What happens to a stationary object if the resultant force is zero?

  It remains stationary
• What occurs to a moving object if the resultant force is zero?

  It continues moving at the same velocity
• What happens to an object's velocity if the resultant force is not zero?

  Its velocity will change
• What must be balanced for a car to travel at a steady speed?

  Resistive forces and driving forces
• What are the possible changes in velocity for an object?

  • Starts to move
  • Stops moving
  • Speeds up
  • Slows down
  • Changes direction
• What must be acting on an object if it is changing its velocity?

  A resultant force must be acting
• What is momentum?

  A property of all moving objects
• What type of quantity is momentum?

  It is a vector quantity
• What does momentum depend on?

  Mass and velocity of an object
• What is the equation for momentum?

  momentum = mass × velocity
• What does Newton's Second Law state about acceleration?

  It is proportional to the resultant force
• What is acceleration inversely proportional to according to Newton's Second Law?

  Mass of the object
• What is the equation linking resultant force, mass, and acceleration?

  F = ma
• What does inertial mass measure?

  How difficult it is to change velocity
• How can inertial mass be calculated?

  inertial mass = force / acceleration
• What does the Law of Conservation of Momentum state?

  Total momentum before equals total after
• How can the conservation of momentum be expressed for two colliding objects?


  m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
• What do the symbols m₁ and m₂ represent in the momentum equation?

  Mass of object 1 and object 2
• What do the symbols u₁ and u₂ represent in the momentum equation?

  Initial velocity of object 1 and 2
• What do the symbols v₁ and v₂ represent in the momentum equation?

  Final velocity of object 1 and 2
• What does Newton's Third Law state about forces?

  They are equal and opposite
• What do force pairs in Newton's Third Law do?

  Act on separate objects
• What is true about the size of force pairs?

  They are the same size
• In which direction do force pairs act?

  In opposite directions
• What type of forces can be in a force pair?

  Same type, like gravitational forces
• What are the revision tips for physics formulas?

  • Use formulas for text and calculation questions
  • Remember: any number multiplied by zero is zero
  • Momentum of a non-moving object is zero
  • Force from a non-accelerating object is zero