Forces and Motion

    Cards (32)

    • A vector has direction and magnitude
    • Examples of vectors - velocity, displacement, acceleration,
      Momentum, force
    • A scalar has a magnitude and no direction
    • Examples of scalars - speed, distance, time, mass, energy
    • Displacement time graphs -
      Gradient is velocity
      Curved line means the velocity is changing (acceleration )
      Horizontal line means stationary
    • displacement is the change in an objects position
    • Velocity time graphs -
      Gradient is acceleration
      Curved line means that acceleration is changing
      Horizontal time means constant speed
      Area under line means distance travelled
    • Speed = distance
      Time
    • Constant speed -
      Measure distance traveled
      Use stopwatch for time taken
    • Newton’s first law -
      An object has a constant velocity unless acted on by a resultant force
    • Newton’s second law -
      Force = mass x acceleration
    • Weight = mass x gravitational field energy
    • Circular motion -
      An object is moving in a circle at a constant speed
      Speed is constant but direction is changing which means it’s accelerating
    • A centripetal force is any force which acts towards the centre of a circle.
    • Internal mass is a measure of how different it is to change the velocity of an object
    • Internal mass = force
      Acceleration
    • Newton’s third law -
      when two objects interact, their forces on each other are equal and opposite
    • Momentum = mass x velocity
    • Momentum is conserved during collisions meaning it is the same before and after
    • Force = change in momentum
      Time
    • Human reaction time -
      There is a delay between when someone sees and acts
      Average rate of reaction is 0.25 seconds
    • Stopping distance = thinking distance
      breaking distance
    • Thinking distance can be affected by influence of drugs or alcohol, tiredness or distractions
    • Braking distance can be affected by road conditions, speed or mass
    • During a crash there is a large deceleration over a short period of time which means a greater force is exerted and able to injure
    • Work done is the energy transferred by a force acting over a distance.
    • Work done = force x displacement ( energy transferred )
    • Weight is the force acting on an object due to gravity
    • Velocity is the rate of change of displacement
    • Speed is the rate of change of distance
    • Kinetic energy = 0.5 x mass x speed2
    • Safety within cars - seatbelt, airbag, crumple zone