Topic 2

    Cards (44)

    • Scalar quantity
      • A quantity that only has a magnitude
      • A quantity that isn't direction dependent
    • Vector quantity
      A quantity that has both a magnitude and an associated direction
    • How vector quantities are represented
      • Using vector arrows
      • The length of the arrow represents the magnitude
      • The arrow points in the associated direction
    • Vector quantities
      • Velocity
      • Displacement
      • Force
    • Velocity
      The speed of an object in a specific direction
    • Gradient of distance/time graph
      The speed
    • Gradient of displacement/time graph
      The velocity
    • Calculating speed at a given time from a distance-time graph for an accelerating object
      1. Draw a tangent to the curve at the required time
      2. Calculate the gradient of the tangent
    • Calculating distance from a velocity-time graph
      It is equal to the area under the graph
    • Gradient of velocity/time graph
      The acceleration
    • Typical value for speed of sound
    • Typical value for human walking speed
    • Typical value for human running speed
    • Typical value for human cycling speed
    • Approximate value for acceleration of an object in free fall under gravity near the Earth's surface
    • Resultant force
      The single force that is equivalent to all the other forces acting on a given object
    • Newton's first law for a stationary object

      If the resultant force on a stationary object is zero, the object will remain at rest
    • Newton's first law for a moving object
      If the resultant force on a moving object is zero, the object will remain at constant velocity (same speed in same direction)
    • Newton's Second Law
      Resultant force = Mass x Acceleration (F = ma)
    • Newton's Second Law in words
      An object's acceleration is directly proportional to the resultant force acting on it and inversely proportional to its mass
    • Weight
      The force that acts on an object due to gravity and the object's mass
    • Quantities weight depends on
      • The object's mass
      • The gravitational field strength at the given position in the field
    • Unit for weight
      Newton (N)
    • Equipment to measure weight
      A calibrated spring-balance or newton-meter
    • Constant speed
      When an object is travelling at a constant speed but not a constant velocity
    • When an object is travelling at a constant speed but not a constant velocity
    • Circular motion
      • Speed is a scalar quantity
      • Velocity is a vector quantity which means it can only be constant if the direction is constant
      • In circular motion, the direction is continuously changing
      • Velocity is constantly changing
    • Centripetal force
      The resultant force that acts on an object moving in a circle, and it acts towards the centre of the circle
    • Inertial mass
      • A measure of how difficult it is to change a given object's velocity
      • The ratio of force over acceleration
    • Newton's Third Law
    • Momentum
      Mass x Velocity
    • The unit used for momentum is kgm/s (kilogram metres per seconds)
    • In a closed system, the total momentum before and after a collision is equal
    • Equation linking change in momentum, force and time
      • Force x Time = Change in Momentum
      • F Δt = mΔv
    • Measuring human reaction times
      1. Using the ruler drop test
      2. Person A and B hold each end of a ruler with the 0 cm mark at the bottom
      3. Person A drops the ruler without telling person B
      4. Person B catches it
      5. The distance travelled corresponds to their reaction time
    • Why it is important that the 0cm mark is at the bottom
    • Stopping distance
      The sum of thinking distance and braking distance
    • For a given braking distance, if the vehicle's speed is increased
      The stopping distance is increased
    • Typical range of values for human reaction time
    • Factors which can affect a driver's reaction time
      • Tiredness
      • Drugs
      • Alcohol