Unit 2.1 - Distance, Speed and Acceleration Flashcards
What is the distinction between speed and velocity?
Speed is scalar (only has magnitude - it is how fast an object moves); velocity is vector (has direction and magnitude - it is how fast an object moves in a given direction).
How can the distance traveled be calculated from a velocity-time graph?
The area under the line represents the distance traveled.
Describe how the principles of forces and motion affect safe stopping of vehicles.
Danger when stopping a vehicle is due to the resultant force on the occupants, and resultant force = change in velocity/time, so the greater the speed of the vehicle, the more dangerous a crash would be.
What factors affect thinking distance?
Reaction time of the driver (which can be affected by tiredness and alcohol), distractions (e.g. mobile phones) and speed of the car.
What factors affect braking distance?
Worn brakes, wet/icy road, mass of the car, worn tires, and speed of the car.
Name three safety features of cars and describe in terms of forces how these keep occupants safe.
Air bags, crumple zones and safety/seat belts - these all increase the time for the change in velocity, reducing resultant force.
What can be introduced in local areas to keep people safe from collisions?
Speed limits and speed bumps - decrease speed of cars, so shorter stopping distance and less chance of collision; also less kinetic energy, so collisions are less dangerous.
