P8.1 Flashcards
How do you convert from mph to km/h?
e.g. 30mph =
30 x 1.6 = 48km/h
How do you convert from km/h to m/s
e.g 48km/h
48/3.6 = 13.33 m/s to 2sf
Give a typical running speed of a person walking in m/s.
walking - 1m/s
running - 5m/s
Give the typical speed of a person cycling in m/s.
cycling - 7m/s
olympic cycling - 20m/s
Give the typical running speed of some strong winds in m/s.
strong wind - 13m/s
Give the typical speed for a car and a train in m/s.
car - 22m/s
train - 56 m/s
What is your reaction time and what experiment can you do to test it?
Your reaction time is the time between you noticing the stimulus and you initiating the response.
To test it do the ruler drop experiment, use v^2 - u^2 =2ad. The acceleration of the ruler is constant and equal to g which is 10m/s^2.
Define thinking distance.
The distance a car travels before the reaction of the driver. E.g the distance between the driver noticing the hazard and the applying the brakes.
What factors influence your thinking distance?
- Reaction time Alcohol Drugs Tiredness - Car speed - In car distractions - Eating or drinking - Using GPS.
Define braking distance.
Distance taken for the car to reach a velocity of zero once the brakes have been applied.
What factors affect breaking distances?
- Speed
- Mass
- Brake condition
- Tyre grip
Define stopping distance.
stopping distance in the total distance the car travels from the time the driver notices the hazard to the car being stationary
How is stopping distance calculated?
Stopping distance = braking distance + thinking distance
Give reasons for why large negative accelerations are dangerous.
You wear a seatbelt which absorbs the force in a collision but it can cause compression injuries and internal organs can be damaged as they move forward in your body even if your ribs have stopped.
What is the purpose of a speed limit?
Speed limits are there to reduce the time taken to stop and speed affects stopping distances a lot.
