DYNAMICS

• What is the definition of a scalar quantity?

  A scalar quantity has magnitude only.
• What is the definition of a vector quantity?

  A vector quantity has both magnitude and direction.
• What are examples of scalar quantities?

  • Speed
  • Distance
  • Mass
  • Time
  • Energy
• What are examples of vector quantities?

  • Velocity
  • Displacement
  • Weight
  • Force
  • Acceleration
• How are vectors added together?

  Vectors are added “tip-to-tail.”
• How is the resultant vector measured?

  The resultant vector is measured from the start of the first vector to the end of the last vector.
• What must all resultant vectors have?

  All resultant vectors must have a three-figure bearing, measured from 000˚ (North).
• What is the process to find a resultant displacement using a scale diagram?

  1. Draw a mini compass.
  2. Choose a suitable scale (e.g., 1cm:1km).
  3. Measure displacement bearing from the starting point.
  4. Quote bearings as a three-figure number.
• What is the formula for distance in terms of speed and time?

  $d =$$v \times t$
• What is the formula for displacement in terms of velocity and time?

  $s =$$v \times t$
• What is the difference between average speed and instantaneous speed?

  Average speed is total distance divided by total time, while instantaneous speed is the speed at any one instant.
• What are the units for average speed?

  Average speed is measured in metres per second (ms^-1).
• What is the purpose of an experiment to measure average speed?

  To measure the total distance an object travels and the total time taken to travel that distance.
• What is one method to measure average speed using a trundle wheel and stop clock?

  • Use a trundle wheel to measure distance (d).
  • Use a stop clock to measure time (t).
  • Calculate average speed using $v =$$\frac{d}{t}$.
• How can light gates be used to measure average speed?

  • First light gate starts the timer.
  • Second light gate stops the timer.
  • Measure distance between light gates (d).
  • Calculate average speed using $v =$$\frac{d}{t}$.
• What is a force?

  A force can change the speed, direction, or shape of an object.
• How is force measured?

  Force is measured in newtons (N).
• What causes friction?

  Friction is caused by two objects moving while in contact with each other.
• In which direction does the force of friction act?

  The force of friction is always in the opposite direction to movement.
• What are some ways to reduce frictional forces?

  • Streamlining
  • Lubrication
  • Smoothing surfaces
• What is required to measure acceleration?

  You need to measure the initial velocity (u), final velocity (v), and time taken (t).
• How can light gates be used to measure acceleration?

  • Light gate 1 measures initial velocity (u).
  • Light gate 2 measures final velocity (v).
  • Timing computer measures time (t).

  
• What information can be obtained from velocity-time graphs?

  • Car speeding up (accelerating) from O to A.
  • Car at constant speed from A to B.
  • Car slowing down (decelerating) from B to C.
  • Displacement = Area under the graph.
  • Gradient gives acceleration.

  
• What is the formula for acceleration?

  $a =$$\frac{v - u}{t}$
• What does the variable 'a' represent in the acceleration formula?

  'a' represents acceleration, measured in metres per second squared (ms^-2).
• What does the variable 'v' represent in the acceleration formula?

  'v' represents final velocity, measured in metres per second (ms^-1).
• What does the variable 'u' represent in the acceleration formula?

  'u' represents initial velocity, measured in metres per second (ms^-1).
• What does the variable 't' represent in the acceleration formula?

  't' represents time, measured in seconds (s).
• How can you measure instantaneous speed?

  • Measure the length of an object (d).
  • Measure the time it takes to pass a point (t).
  • Calculate instantaneous speed using $v =$$\frac{d}{t}$.
• What are balanced forces?

  Balanced forces are two forces that are the same size but act in opposite directions.
• What does Newton's 1st law state about balanced forces and velocity?

  If the forces on an object are balanced, the object will either stay at rest or move with constant velocity in a straight line.
• How can you calculate unbalanced force if given two different forces in opposite directions?

  Unbalanced force can be calculated by subtracting the smaller force from the larger force.
• What does Newton's 2nd law tell us about unbalanced forces and acceleration?

  If the forces on an object are unbalanced, the object will accelerate in the direction of the unbalanced force.
• What is the formula that links unbalanced force, mass, and acceleration?

  $F =$$m \times a$
• What does the variable 'F' represent in the unbalanced force formula?

  'F' represents unbalanced force, measured in newtons (N).
• What does the variable 'm' represent in the unbalanced force formula?

  'm' represents mass, measured in kilograms (kg).
• What does the variable 'a' represent in the unbalanced force formula?

  'a' represents acceleration, measured in metres per second squared (ms^-2).
• What is the formula that links work done, unbalanced force, and distance?

  $E_w =$$F \times d$
• What does the variable 'E_w' represent in the work done formula?

  'E_w' represents work done, measured in joules (J).
• What does the variable 'd' represent in the work done formula?

  'd' represents distance, measured in metres (m).