motion

• Vectors


  Physical quantities that have both magnitude and direction
• Scalars


  Physical quantities that have magnitude but no direction
• Vectors are normally shown with numbers written next to them and the size of vectors in a diagram are always proportional to each other
• Double the length of a vector = double the magnitude (how big it is)
• Scalar quantities


  • speed, volume, the number of pages in your textbook, mass
• Vector quantities


  • displacement, velocity, acceleration, forces
• Vectors in diagrams are shown as arrows pointing in the direction of the vector
• Mass


  A property of objects that has no set direction (scalar)
• Weight


  The force produced when a mass is in a gravitational field, has a direction usually towards the centre of a planet or star (vector)
• Speed


  How fast an object is going, doesn't matter in what direction (scalar)
• Velocity


  Speed and direction (vector)
• Distance


  The total an object has travelled, even if it ends up back at its starting location, doesn't matter what direction (scalar)
• Displacement


  How far from the starting point an object has moved, has direction (vector)
• Displacement is the distance covered in a certain direction, it is therefore a vector
• Runner A finishes a race in less time than runner B, so runner A is faster
• The two measurements needed to calculate speed are distance and time
• Speed unit if time is in hours and distance is in miles

  miles per hour
• The unit for speed used on roads in the UK is miles per hour
• Acceleration


  Speeding up or slowing down
• Force


  A push or pull
• Forces are represented on diagrams as arrows, with length depending on size of force
• Mass


  The amount of substance
• A man runs 45 m in 5 seconds, his speed is 9 m/s
• A dog runs at 5 m/s for 1 minute, the distance he runs is 300 m
• A car travels at 30 km/h and covers 900 km, the time taken is 30 hours
• Calculating distance


  Speed x time
• Calculating time


  Distance / speed
• The steeper the line on a distance-time graph, the faster the object is moving</b>
• The gradient of a distance-time graph gives the speed
• The acceleration, g, in free fall is 10 m/s^2
• v^2 - u^2


  Equation that has these quantities in it
• Car travels 500 metres while accelerating from 5 m/s to 10 m/s


  • Quantities in the question: distance, initial velocity, final velocity, acceleration
• v^2 - u^2 = 2 × a × x


  Equation that has these quantities in it
• Solving question 2


  1. Write the equation

  2. Substitute the numbers

  3. Calculate
• Make sure you write the two velocities in the correct order. The starting velocity is always last.
• Deceleration


  Slowing down, a negative acceleration
• Solving question 4


  1. Write the equation

  2. Rearrange the equation to make t the subject

  3. Substitute the numbers

  4. Calculate
• As temperature increases


  The rate of reaction increases
• Solving question 5


  1. Rearrange the equation to make the change in speed the subject

  2. Substitute the numbers

  3. Calculate
• Solving question 6


  1. Rearrange the equation to make the initial velocity the subject

  2. Substitute the numbers

  3. Calculate