Year 10 Motion Summary

SI Units

• Agreed units of measurement for worldwide use are called SI units.
  • Length: metre (m)
  • Mass: kilogram (kg)
  • Time: second (s)
  • Electric current: ampere (A)
  • Temperature: kelvin (K)
  • Amount of substance: mole (mol)
  • Luminous intensity: candela (cd)
• SI units can be combined for other quantities, e.g., speed = m/s.

Scalars and Vectors

• Scalar quantities: have magnitude only (e.g., length, speed).
• Vector quantities: have both magnitude and direction (e.g., velocity, force).

Distance vs. Displacement

• Distance: total ground covered (scalar quantity).
• Displacement: shortest distance from start to end point (vector quantity).

Speed

• Speed measures how quickly something moves.
• Scalar quantity; can change units (e.g., km/h, m/s).
• Average speed = total distance / total time.

Acceleration

• Rate of change of velocity; vector quantity.
• Can change by speeding up, slowing down, or changing direction.
• Measured in m/s².

Graphs of Motion

• Displacement vs. time graphs (x-t graphs): show position changes; gradient indicates velocity.
• Velocity vs. time graphs (v-t graphs): show speed changes; gradient indicates acceleration.
• Area under graph represents distance traveled.

Summary of Key Concepts

• Average speed vs. instantaneous speed: Average speed is total distance over total time; instantaneous speed is speed at a specific point in time.
• Sonar: technique using sound waves for mapping (e.g., detecting ocean depths).
• Terminal velocity: maximum speed of a falling object when gravity is balanced by air resistance.