Orbits and speed

• What can the movement of objects be described using?

  Motion graphs and numerical values
• Why are motion graphs and numerical values used in vehicle design?

  They help in the design of faster and more efficient vehicles
• What happens to an object's direction when it moves in a circle at constant speed?

  • The direction constantly changes
  • This change in direction causes a change in velocity
• What is velocity?

  The speed of an object in a particular direction
• What is a vector quantity?

  A quantity that has both magnitude and direction
• What is acceleration?

  The rate of change in speed or velocity
• How is acceleration calculated?

  Acceleration = change of velocity ÷ time taken
• What does it mean for an object moving in a circle at constant speed?

  It is accelerating even though its speed may be constant
• What is a resultant force?

  The single force that could replace all the forces acting on an object
• What happens if all the forces acting on an object are balanced?

  The resultant force is zero
• What is the centripetal force?

  The force needed for circular motion that acts towards the center of a circle
• What provides the centripetal force needed to keep a planet in orbit around the Sun?

  Gravitational attraction
• How does gravitational attraction affect the Moon's orbit around the Earth?

  It keeps the Moon in orbit around the Earth
• What is the relationship between speed and velocity for an object in circular motion?

  • Speed remains constant
  • Velocity changes due to changing direction
  • The object is accelerating despite constant speed
• What is the significance of velocity being a vector quantity?

  It depends on both speed and direction
• Why does an object in circular motion experience acceleration?

  Because its velocity is changing due to direction change