chapter 2

• 5 common scalar quantities


  distance, speed, mass, energy, time
• 5 common vector quantities

  displacement, acceleration, weight, force, velocity
• how to find speed?

  distance divided by time taken
• how to find velocity?

  displacement divided by time taken
• vector diagram

  choose an appropriate scale to represent the vectors
• how to find average speed?

  total distance travelled divided by total time taken
• constant or uniform speed


  change in distance travelled by an object for every unit of time is the same
• displacement

  distance measured in a straight line from a fixed reference point
• velocity


  rate of change in displacement
• how to find acceleration?

  velocity divided by time taken
• constant or uniform acceleration

  change in velocity of an object per unit time is the same
• how to find acceleration?

  (final velocity minus initial velocity) divided by change in temperature
• non uniform acceleration

  change in velocity per unit time is not the same
• displacement time graph

  gradient of the graph is the velocity of the object

  • when gradient is zero, velocity is zero, object is at rest
  • when gradient is constant, uniform velocity
  • when gradient is increasing, velocity is increasing, non uniform velocity
  • when gradient is decreasing, velocity is decreasing, non uniform velocity
• velocity time graph

  gradient of the graph is the acceleration of the object

  • when velocity and gradient is zero, acceleration is zero, car at rest
  • when only gradient is zero, car is moving but acceleration is zero
  • when gradient is positive and constant, acceleration is constant
  • when gradient is negative and constant, deceleration is constant
  • when gradient is positive and increasing, acceleration is increasing
  • when gradient is positive and decreasing, acceleration is decreasing
• 10m/s^2

  acceleration of free fall for a body near to Earth is constant

  acceleration due to gravity for objects on Earth is constant
• What is the formula to find acceleration?

  acceleration = (final velocity – initial velocity) / time taken
• How does the initial velocity affect the calculation of acceleration?

  A higher initial velocity increases the final result
• What is the unit of acceleration?

  m/s²
• What is displacement in physics?


  Change in position from starting point
• What does a constant gradient on a displacement-time graph signify?

  The object has uniform velocity
• What does a positive gradient on a displacement-time graph indicate?

  The object is moving in a positive direction
• What can be inferred if the gradient of a displacement-time graph is negative?

  The object is moving in the opposite direction
• What does a positive and increasing gradient indicate?

  Acceleration is increasing
• What does it indicate when only the gradient is zero on a velocity-time graph?

  Car is moving but acceleration is zero
• What does a horizontal line on a velocity-time graph represent?

  Zero acceleration (constant velocity)
• What does a flattening line on a velocity-time graph indicate?

  Decreasing acceleration
• What is the significance of the constant acceleration due to gravity?

  • It is approximately $10 m/s²$ or $9.81 m/s²$
  • Objects fall at the same rate without air resistance
  • Essential for understanding motion near Earth's surface
• What does a decreasing gradient on a displacement-time graph signify?

  The velocity is decreasing, non-uniform
• What does the acceleration formula calculate?

  Change in velocity per unit time
• What does an increasing gradient on a displacement-time graph indicate?

  The velocity is increasing, non-uniform
• What does a positive and constant gradient indicate?

  Acceleration is constant
• What does a negative and constant gradient indicate?

  Deceleration is constant
• How is velocity defined in relation to displacement?

  Rate of change in displacement over time
• What does a positive and decreasing gradient indicate?

  Acceleration is decreasing
• What does the dynamic change in acceleration indicate?

  It shows non-uniform acceleration
• Why do objects fall at the same rate near Earth's surface?

  Because they experience the same acceleration
• What are the characteristics of a velocity-time graph with constant acceleration?

  • Shows a straight line
  • The slope of the line represents acceleration
  • The line represents constant rate of change in velocity
• How does a velocity-time graph represent motion with constant acceleration?

  It shows a straight line with a constant slope.
• What does non-uniform acceleration mean?

  Change in velocity per unit time is not constant