forces and breaking

• What is a force?


  A push or pull that can cause an object to accelerate, decelerate, change direction, or change shape
• In what unit is force measured?


  Newtons (N)
• What are the two types of forces?

  Contact forces and non-contact forces
• What is the stopping distance of a vehicle?


  The total distance a vehicle travels before it comes to a complete stop after the driver reacts
• What is the equation for stopping distance?


  Stopping distance = thinking distance + braking distance
• What is thinking distance?


  The distance travelled by a vehicle during the driver's reaction time after spotting a hazard
• What factors affect thinking distance?

  Reaction time and speed of the vehicle
• What is reaction time?


  The time it takes the driver to respond to a situation
• How does speed affect thinking distance?


  The faster the vehicle, the longer the thinking distance
• What are some factors affecting reaction time?


  Tiredness, alcohol or drugs, distractions, age, and alertness
• What is braking distance?


  The distance a vehicle travels while the brakes are applied until it comes to a stop
• What factors affect braking distance?


  Speed of the vehicle, mass of the vehicle, condition of brakes, condition of tires, road surface, and weather conditions
• How does speed affect braking distance?


  A higher speed means more kinetic energy, so it takes longer to stop
• How does mass affect braking distance?


  A heavier vehicle will take longer to stop
• How do worn-out brakes affect braking distance?


  Worn-out brakes are less effective, increasing braking distance
• How do worn-out tires affect braking distance?


  Worn-out tires have less grip, increasing braking distance
• How does road surface affect braking distance?


  Wet, icy, or uneven surfaces increase braking distance
• How do weather conditions affect braking distance?


  Rain or snow makes roads slippery, increasing braking distance
• What is kinetic energy?


  The energy an object has due to its motion
• What must happen to kinetic energy for a car to stop?


  Kinetic energy must be reduced to zero
• What is the equation for kinetic energy?


  KE = \frac{1}{2} m v^2
• What do brakes do to reduce a car's kinetic energy?


  The brakes do work to reduce the car's kinetic energy and bring it to a stop
• What is the equation for work done by brakes?


  Work done = braking force x braking distance
• What factors affect stopping distance?


  Speed, mass of the vehicle, road conditions, tire condition, and weather