topic 9

• Quantities that have magnitude only.


  What are scalars?
• Quantities that have magnitude and an associated direction.


  What are vectors?
• Distance, speed and time.

  Give 3 examples of scalars.
• Displacement, velocity, acceleration, force and momentum.

  Give 5 examples of vectors.
• gradient


  The speed of an object can be determined from the _______ of a distance-time graph.
• speed

  If an object is accelerating, its ________ at any particular time can be found determined by finding the gradient of the tangent of the distance-time graph at that time.
• its speed in a given direction.


  The velocity of an object is...
• gradient, velocity-time


  The acceleration of an object can be determined from the ______ of a _______-_______ graph.
• area under


  The distance travelled by an object can be determined by the ____________ a velocity-time graph.
• the forces they exert on each other are equal and opposite.

  Whenever two forces interact...
• A number of forces acting at a point being replaced by a single force that has the same effect on the motion as the original forces all acting together.


  What is a resultant force?
• the object will remain stationary.


  If the resultant force acting on a stationary object is zero...
• the object will accelerate in the direction of the resultant force.


  If the resultant force acting on a stationary object is not zero...
• the object will continue to move at the same speed and in the same direction.

  If the resultant force acting on a moving object is zero...
• the object will accelerate in the direction of the resultant force.

  If the resultant force acting on a moving object is not zero...
• greater, braking

  The greater the speed of a vehicle, the _______ the ________ force needed to stop it in a certain distance.
• the sum of the distance the vehicle travels during the driver's reaction time (thinking distance) and the distance it travels under the braking force (braking distance).

  The stopping distance of a vehicle is... (longer answer)
• thinking distance + braking distance

  The stopping distance of a vehicle is... (shorter answer)
• Tiredness, alcohol and drugs.

  Name 3 things a driver's reaction time can be affected by.
• work done, friction, wheel, kinetic, brakes

  When the brakes of a vehicle are applied, _____ _____ by the _______ force between the brakes and the ______ reduces the ________ energy of the vehicle and the temperature of the _______ increases.
• work done by the friction fore between the brakes and the wheel reduces the kinetic energy of the vehicle and the temperature of the brakes increases.

  When the brakes of a vehicle are applied...
• Adverse weather conditions (wet or icy) and poor condition of the vehicle (brakes or tyres).

  Name 2 things that can affect a vehicle's braking distance.
• frictional


  The faster an object moves, the greater the ________ force which acts on it.
• fluid, gravity, resultant, terminal velocity

  An object falling through a _____ will initially accelerate due to the force of _______. Eventually the __________ force will be zero and the object will move at its _________ _________.
• 1. Body accelerates

  2. Speed increases with a constant acceleration

  3. Air resistance increases as velocity increases

  4. The gravitational force is still greater than the resistive forces however acceleration is less

  5. Eventually you reach terminal velocity, meaning the gravitational forces are equal to the resistive forces


  List the order of the 5 things that happen when you jump out of a plane (without opening a parachute)
• 1. Parachute is opened so surface area increases

  2. Velocity slows to a new terminal velocity


  What two things happen when you open a parachute when jumping out of a plane?
• shape


  A force acting on an object may cause a change in the ______ of the object.
• it returns to its original shape when the force acting on it is removed.

  An object behaves ELASTICALLY if...
• stretching and storing elastic potential energy.


  A force applied to an elastic object such as a spring will result in the object...
• extension, force applied


  For an object behaving elastically, the ________ is directly proportional to the _____ ________, provided that the limit of proportionality is not exceeded.
• a force causes an object to move through a distance.


  Work is done when...
• Energy


  ________ is transferred when work is done.
• heating

  Work done against frictional forces causes energy transfer by _______.
• 1. Work is done by friction between the brakes and the wheel of a car

  2. Kinetic energy of the car is reduced

  3. Transferred by heating

  Give an example of when work done causes something to become hot
• Work is done against the gravitational force and the object gains gravitational potential energy.


  What happens when an object is raised vertically?
• double


  An object of double the mass of another object travelling with the same speed has ______ the kinetic energy.