Chapter 3 - Motion Flashcards
Definition of Speed, Equation and SI
rate of change of distance, v=d/t, ms^-1
Definition of instantaneous speed and how to determine
Speed of an object over a very short time and can be determined by the gradient of a distance time graph at a given time
Definition of velocity, vector or scalar? Equation
Rate of change of displacement,
vector,
change in displacement / time
Definition of acceleration, vector or scalar? When does acceleration change
rate of change of velocity, vector, when speed changes or direction e.g. circular motion
What is the main assumptions when tackling projectiles?
Negligible air resistance
horizontal component
cos
vertical component
sin
What happens to horizontal velocity through motion and why?
Remains constant as no force is acting in horizontal plane
Define stopping distance
Total distance travelled from when the driver of the car sees a hazard requiring them to stop, to the point where the car stops
Define thinking distance
Distance travelled between the hazard being seen and the brakes being applied
Define braking distance
Distance travelled from the time the brakes are applied to when the car stops
Equations for thinking distance
- thinking distance is proportional to initial speed
- initial speed x reaction time
Factors affecting thinking distance
- Drugs
- Tiredness
- Distractions e.g. phone, other people
Equation for braking distance and reason
- Braking distance is proportional to initial speed squared
- In order for the car to stop, all of it’s kinetic energy needs to be dissipated, therefore 1/2mv^2
Factors affecting braking distance
- poor road conditions
- tyre conditions
- brake pad conditions
- weight
