P8.1 Flashcards
What does accurate mean?
How close the value are to the true values
What does precise mean?
How close values are to each other
How many metre in a mile?
1609
How would you measure the speed of a car?
Speed camera or speed gun
Use a trundle wheel to measure the distance between marks on a road and use the time between 2 photos to work out distance and time
How would you measure the speed of a runner?
Measure the distance of the race track and use pressure pads for time
How would you measure the speed of a cyclist?
Wheel circumference for distance and magnetic sensors to detect each rotation
How fast does a person walk or run?
1m/s and 5m/s
How fast is an Olympic cyclis?
20m/s
How can you measure reaction time?
Catching a falling ruler
What is thinking distance?
The distance travelled by a vehicle in the time it takes for a driver to see an event and apply a force to the brakes. It is directly proportional to speed
What is typical human reaction speed?
0.2-0.8 seconds
What factors effect thinking distance?
Blood alcohol levels Tiredness Drugs both legal and illegal Distraction Using a radio or phone
How do you calculate thinking distance of a car travelling at 50mph?
Convert to m/s - 50x1609/3600
Distance= speed x time - Assume that time is 0.2 seconds
What is braking distance?
The distance a vehicle travels while a force is applied to the brakes
What factors affect braking distance?
Road conditions
Speed
Quality of brakes and tires
What is stopping distance?
The total distance that a car travels from the moment the driver sees an event
Thinking distance + braking distance
What is the Highway Code acceleration?
-6.6m/s
Why are large decelerations dangerous?
The force exerted by the seat belt can cause compression injuries and injure organs
Why do Seatbelts stretch ?
To increase the time taken to come to a halt which decreases the force. They must be replaces after an accident
What are crumple zones and air bags for?
To increase the time taken for the car to come to a halt and the driver to hit the steering wheel. Force is inversely proportional to time so the more time the less force
