Distance, speed and acceleration. Flashcards
What is acceleration?
The rate of change of velocity measured in metres per second squared.
What is distance?
Measured in metres, its how far an object travels or how far away an object is from a fixed point.
What is time?
Measured in seconds, it is the time interval between 2 events or the time since the start of the motion.
What is speed?
Measured in metres per second, it is a measure of how fast or slow the object is moving.
What is the equation that links speed?
Speed = distance/time
What is velocity?
Measured in metres per second in a given direction, a measure of how fast or slow the object is moving in a given direction (eg north/south, left/right).
What is the equation regarding acceleration?
Acceleration or deceleration = change in velocity/time
What type of quantity is speed?
Speed is a scalar quantity because it only has magnitude.
What type of quantity is velocity?
Velocity is a vector quantity because it has direction as well as magnitude.
What are the 2 types of motion graphs?
Distance/time and velocity/time graphs.
What does a distance/time graph allow us to do?
Measure the speed of a moving object.
How are stationary objects represented in distance time graphs?
As a horizontal line.
What does the gradient of a velocity time graph show us?
The gradient is the acceleration of the object.
How do you find the distance travelled in a velocity/time graph?
The area under the velocity time graph.
What is total stopping distance made up of?
Thinking distance and braking distance.
What is thinking distance?
The distance the vehicle travels while the driver sees the hazard, thinks about braking and then actually reacts by braking.
What is braking distance?
The distance the vehicle moves while the brakes are applied and the vehicle is decelerating to 0 m/s.
Factors effecting thinking distance?
- The velocity of the car
- The awareness of the driver, if they are under any influences.
- The reaction time of the driver.
Factors effecting braking distance?
- The velocity and mass of the car.
- The conditions of the brakes.
- The conditions of the tires.
- The condition of the roads.
- The weather.
How do you minimise injuries on occupants in a sudden stop?
Reduce the forces acting on them, increase the time of the collision.
What is the equation regarding Newton’s second law?
resultant force = change in momentum/ time for change.
How do you reduce the force on an occupant?
Reducing the speed of the collision, so reducing the change in momentum.
Increasing the time of the collision.
How do certain safety features on cars increase times of a collision?
Allowing something to be deformed.
- seat belts stretch
- airbags slowly deflate
- crumple zones crumple in on themselves
What are the 2 main traffic control features that control speed?
Speed bumps and speed limits
