our dynamic universe

• What must be written beside every final answer in physics?

  The correct unit
• What is the prefix for Terra?

  T = x $10^{12}$
• What is the prefix for milli?

  m = x $10^{-3}$
• Why must prefixes be converted before calculations?

  To ensure full marks are awarded
• How many significant figures should final answers typically have?

  Three significant figures
• What should not be rounded up in calculations?

  Intermediate answers
• What is the uncertainty in a digital device measurement?

  ± 1 in least significant digit
• How is reading uncertainty determined for analogue devices?

  ± half the smallest division
• What are systematic uncertainties?

  Uncertainties caused by consistent measurement errors
• What is random uncertainty?

  Uncertainty that occurs when repeating measurements
• How do you calculate random uncertainty?

  Using the equation: $\frac{max. value - min. value}{number of values}$
• How should the final answer for random uncertainty be expressed?

  In absolute form
• What does a large random uncertainty indicate?

  More repeated readings will reduce it
• How do you convert absolute uncertainty to percentage uncertainty?

  Using the equation: $\frac{uncertainty}{mean value} \times 100\%$
• What is a scalar quantity?

  A quantity with magnitude only
• What is a vector quantity?

  A quantity with magnitude and direction
• How are vector quantities added?

  Using the tip-to-tail method
• What is the resultant vector?

  The result of adding original vectors
• How do you find the resultant vector at right angles?

  Using Pythagoras and trigonometry
• What is the equation for finding the direction of a vector?

  $\tan \theta =$$\frac{opp}{adj}$
• What must be labeled on a vector diagram?

  The angle θ or a three-figure bearing
• What to do if vectors are not at right angles?

  Use a scale drawing to find the resultant
• What is speed defined as?

  Distance travelled per second
• What is the equation for speed?

  $d =$$vt$
• What is velocity defined as?

  Displacement travelled per second
• What is the equation for velocity?

  $s =$$vt$
• What is a vector component?

  A split of a vector into horizontal or vertical parts
• What are the equations for horizontal and vertical components?

  $v_H =$$v \cos \theta$ and $v_V =$$v \sin \theta$
• What are the four equations of motion?

  v = u + at, s = ut + ½ at$^2$, v$^2$ = u$^2$ + 2as, s = ½(u + v)t
• What should you write before solving motion problems?

  Write s, u, v, a, t
• What does the gradient of a displacement-time graph represent?

  The velocity of the object
• What does a negative displacement indicate?

  A change in direction
• What does a diagonal line in a displacement-time graph indicate?

  A constant velocity
• What does a curved line in a displacement-time graph represent?

  An increasing or decreasing velocity
• What does the gradient of a velocity-time graph represent?

  The acceleration of the object
• What does the area under a velocity-time graph represent?

  The displacement travelled
• What does a line cutting the time-axis in a velocity-time graph indicate?

  A change in direction
• What does a horizontal line in an acceleration-time graph indicate?

  A constant acceleration
• What does the area under an acceleration-time graph represent?

  The velocity of the object
• What should be considered when interpreting acceleration-time graphs?

  Deceleration can also be acceleration in the opposite direction