P8.1 Flashcards
Equipment to measure the speed of a sprinter
- electronic timing
- measuring tape / TRUNDLE WHEEL
- pressure sensor to start + break laser beam to end
Equipment to measure the speed of a car on a road
- speed camera
- trundle wheel
- time between two photos
Equipment to measure the speed of a cyclist
- wheel sensor
- when diameter
- magnetic sensor detecting one rotation
Typical walking speed
1m / s OR 2.2 mph
Typical running speed
5m/s OR 11mph
Typical cycling speed
7m/s or 15mph
Typical cycling speed - in olympics
20m/s or 45mph
Typical speed of strong wind
13m/s or 30mph
Typical speed of a car
22m/s or 50mph
Typical speed of a train
56m/s or 125mph
SPEED OF SOUND
330m/s
How to convert from mph to m/s
Define thinking distance
Distance car travels whilst driver is reacting.
thinking about stopping
Define BRAKING DISTANCE
Distance car travels whilst driver applies the brakes.(whilst braking force acts)
What is stopping distance
STOPPING DISTANCE = THINKING + BRAKING DISTANCE DISTANCE
Factors effecting thinking distance
ie. effect the DRIVER
- tiredness / energy levels
- alcohol
- drugs
- distraction
Factors effecting braking distance
- weather = wet or dry roads
- worn tyres
- faulty breaks
- badly maintained roads
Why does the braking distance of a car increase if the road is wet?
The distance increases because the force of friction between tyres and road decreases.
What’s the key word when they ask you about thinking or braking distance
DISTANCE!!
it’s DISTANCED TRAVELLED not TIMEEEE!
What does the area under a velocity - time graph show
Distance
Why is a large negative acceleration dangerous - without a seatbelt
If the car slows down suddenly the belt exerts a force on you. Without it you would continue to move with your original speed, and could collide with the dashboard or the seat in front of you, causing injury to yourself or others.
Why is a large negative acceleration dangerous - with a seatbelt
If your deceleration (negative acceleration) is very large the seatbelt can cause compression injuries. Also, you can injure your internal organs because they continue to move inside your body even if your ribs are stopped by the seatbelt.
Cool textbook fun fact
If the acceleration that you experience is about twice the acceleration due to gravity (g = 9.81 m/s7), you feel a force equal to twice your weight, which people sometimes call ‘2g. You experience accelerations of about 5g on some rollercoasters.
