Motion and forces

• how do u calculate speed

  speed = distance / time
• Why does circular motion happen

  For circular motion to occur there must be a force acting inwards along the radius of the circle , this is called the centripetal force . The object moves at a right angle to this force
• What is mass


  Mass is a measure of the amount of matter contained within a three-dimensional space
• What happens to a body moving in circular motion

  A body moving in a circular path with constant speed still has a changing velocity because its direction is always changing therefore it is constantly accelerating
• What is the equation for force involving momentum and time

  Force = Change in momentum / Time taken f = mv - mu/t
• What is thinking distance

  The distance the car travels while the driver applies the breaks and responds to danger
• What is the difference between a scalar and a vector quantity

  Scalars have a magnitude but no specific direction whereas vectors have both magnitude and a specific direction
• Give examples of scalars and vectors


  Scalar : mass , speed , energy , temperature

  Vector : Force/Weight , velocity , displacement , acceleration , momentum
• What is velocity


  velocity is speed in a stated direction
• How do u calculate overall speed and distance travelled

  average speed = total distance travelled / time

  total distance travelled (m) = average speed * time taken
• How do you calculate acceleration

  acceleration = change in velocity/time
• What is the equation for velocity

  final velocity 2 - initial velocity 2 = 2 x distance x acceleration
• How do u find acceleration and distance from a velocity/time graph

  The gradient tells us about the acceleration and the area under the graph tells us about the distance travelled
• What does newtons first law state

  Newtons first law states that a body will remain at constant speed in a straight line unless acted upon by a resultant force . When resultant force is 0 the body is at rest or constant velocity. When the resultant is not 0 the speed and/or direction of the body changes
• What does Newtons 2nd law state


  When a resultant force acts on a body there will be a change in its velocity . The resultant force determines the size and direction of the subsequent acceleration of the mass
• How do you calculate force using mass and acceleration

  Force (N) = Mass (kg) x Acceleration (m/s 2 )
• What is inertial mass


  Inertial mass is a measure of how difficult it is to change the velocity of a moving object
• What is weight


  Weight is the force a body experiences due to its mass and the size of the gravitational field strength
• What is the formula for weight

  Weight (N) = Mass (kg) x Gravitational field strength
• Describe the relationship between weight and gravitaitional field strength

  Weight is directly proportional to gravitational field strength
• How do u calculate momentum

  momentum (kgm/s) = mass (kg) x velocity (m/s) p = mv
• What does newtons 3rd law state

  Newtons 3rd law states that for every action there is an opposite and equal reaction . The reaction and action forces act on both bodies
• How does momentum change during A collision

  momentum is conserved . Total momentum before a collision is always equal to the total momentum after a collision
• What could affect a humans reaction time

  tiredness

  distractions

  alcohol/drugs

  age
• Devise a method on how to measure reaction time

  RULER DROP TEST A metre ruler is held by a partner so that its vertical and level with the persons thumb and finger with the lowest number at the bottom . Ruler is dropped and the end is grasped by the other person . Finally use the reaction time equation
• What is a stopping distance

  Total distance over which a vehicle comes to rest
• What could affect stopping distance

  Vehicle mass Vehicle speed Amount of friction between the tires and road
• What is breaking distance

  The distance the car travels while its slowing down
• What factors affect thinking distance

  Driver is tired

  Driver is distracted

  Driver is intoxicated
• How does breaking distance Increase

  Breaking distance increases when the friction between the tires and road decreases.
• How does a vehicle come to rest

  Work must be done on the vehicle . When a force is applied to the brakes the kinetic energy is transferred to thermal energy and the vehicle comes to rest over a certain distance
• What equation governs work done on a vehicle

  work done = mass x $velocity^2$