CP2: Motion and forces

• What is the difference between vector and scalar quantities?

  Vector quantities have both magnitude and direction, while scalar quantities only have magnitude.
• give examples of vector quantities:

  Displacement, velocity, acceleration, force, weight and momentum
• give examples of scalar quantities:


  distance, speed, mass and energy
• What is a resultant force?

  The overall force acting on an object, taking into account both magnitude and direction.
• How do calculate resultant forces?


  By adding The individual forces
• What is velocity?


  Speed in a stated direction
• what is the equation for speed?

  (average) speed (m/s)= distance (m)/ time (s)
• what is the equation for distance?

  Distance travelled (m)= average speed (m/s) x time (s)
• How do you calculate acceleration?

  Acceleration (m/s squared) = change in velocity (m/s)/ time taken (s)

  a= (v-u)/ t
• How do you calculate final velocity?


  (final velocity)2 – (initial velocity)2 = 2 × acceleration × distance
• How do you interpret acceleration from gradients?


  The gradient of the line is equal to the acceleration, so the greater the acceleration the greater the gradient Acceleration = change of velocity ÷ time taken
• what is acceleration of freefall?

  10m/s^2
• what is the application of newtons first law when the resultant force on the body is zero?


  • a stationary object stays stationary
  • a moving object continues to move at the same velocity (at the same speed and in the same direction)
• what is newtons second law?

  resultant force (N) = mass (Kg) × acceleration (m/s^2)

  The acceleration of an object increases if the resultant force on it increases, and decreases if the mass of the object increases.
• what is weight?


  The force that a body experiences due to its mass and size of the gravitational field that it is in.

  weight (N) = mass (Kg) × gravitational field strength (N/Kg)
• What is momentum?

  The product of an object's mass and velocity.
• how do you calculate momentum?

  momentum = mass × velocity

  p (kg m/s) = m (kg) x v (m/s)
• What is the stopping distance?

  stopping distance = thinking distance + braking distance
• how is the stopping distance affected by the mass of the vehicle? 


  A vehicle with a larger mass is harder to stop as more friction is required.
• what is Newton’s first law?

  An object has a constant velocity unless acted upon by a resultant force
• What happens if the resultant force on an object is not zero?

  It will accelerate, and because acceleration is a change in velocity over time the velocity will change so the direction and speed of the object will change too.
• what happens if the resultant force on an object is zero?


  no acceleration so if its moving it will move at a constant velocity (same speed and direction) or if it is not moving stay at rest (no speed)
• What is velocity?


  the speed of an object in a specific direction
• What is meant by constant velocity?


  Unchanging speed and direction.
• What is Newton’s second law?

  force = mass x acceleration
• What are the six key facts about distance time graphs?


  • Horizontal (across line ————-) = stationary
  • straight sloping line / = moving at a constant/steady speed
  • to find speed = find gradient (rise/run)
  • greater the gradient = faster the movement
  • if the line is curved down then up / ) = accelerating
  • if the line is curved up then down / ( = decelerating
• What are the six key facts about velocity time graphs?

  • Horizontal line (across ——) = constant velocity
  • sloped line / = acceleration
  • area under the line = distance travelled
  • Sloped line \ = deceleration
  • 0 velocity = stationary
  • curved line = acceleration changing
• What is the acceleration of freefall of earth?

  10 m/s^2
• What is the experiment to explore the Relationship between force, mass and acceleration?

  • Set up two light gates one at the start one at the end
  • measure the distance in between them
  • Measure time taken for the trolley to reach the second after passing the first light gate
  • Use speed = distance ÷ time
• What is the effects of newtons second law (4 types)?

  • object is stationary= start moving in the direction of the resultant force
  • object is in the direction of the resultant force= speed up
  • Objects is moving in the opposite direction to the resultant force= slow down or stop moving or change direction
• what is the centripetal force?

  the force acting inwards that causes circular motion
• what direction does the object move to centripetal force?

  right angle
• what happens in circular motion?

  • the centripetal force causes the speed to be constant
  • but the direction changes because it is going in a circle
  • so the velocity is always changing because the direction is always changing
  • Because the velocity is changing the object is accelerating
• what is inertia?


  the application of newtons 1st law

  objects at rest stay at rest

  objects that are moving stay moving
• what is inertial mass?

  how hard it is to change the objects velocity

  found by: force ÷ acceleration
• what is newtons 3rd law?

  When two objects interact the forces they exert are opposite and equal

  opposite refers to direction

  equal refers to magnitude/size
• What is momentum? 


  Defined by Mass x velocity
• What is the principle of conservation of momentum?


  In a closed system:

  total momentum before = total momentum after
• What is the average human reaction time?

  0.25s
• what factors effect thinking distance?

  • speed
  • reaction time
  • concentration
  • tiredness
  • distractions
  • influence of drugs/alcohol