Forces 2

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• Forces 2
• 1) Why is the resultant force zero on a steadily moving car? What are the forces on a car called? What is the acceleration equation?
• F=ma, when a vehicle is traveling at a steady speed, force =0 because the engine thrust force is equal to the air resistance force.
• a=v-u/t
• 2) How do you interpret a speed/time graph for   thinking, braking and stopping distance?
• Thinking time is the horizontal part where the gradient=0, and thinking distance is the area underneath.
• Breaking time is the part of the line with the negative gradient, and breaking distance is the area underneath.
• Stopping distance is the area under the line of the whole graph.
• 3a) Name 3 factors that affect the braking distance:
• Road condition, weather (e.g rain), condition of breaks.
• 3b) Name 3 factors that affect thinking distance:
• Use of drugs or alcohol, tiredness, distractions in the car, (e.g phones, children)
• 3c) What are the two factors that affect stopping distance the most?
• The speed of a vehicle when the brakes are applied, and the condition of the vehicle.
• 4) Why do the brakes of a car heat up when applied?
• Because the kinetic energy of the car is transferred to heat energy when the brakes are applied, because of the friction between the brakes and the tyres.