p8 Flashcards
what are some of the typical speeds in eberyday for walking, running, cyling and other transportation systems?
what are some of the typical speeds for wind, sound?
what are the magnitudes of everyday accelerations?
chnage in speed/ time
guess time as 10s, 100s, 10,000s ….
what ares some methods for measuring human reaction?
ruler falling test:
a person holds a ruler just above your hand and then drops it. The length of the ruler indicates the reeaction time
what is the typical human reaction time?
0.2 seconds
What is breaking distance
Distance the car travels when a driver applies the break.
Machine role
What is the stopping distance
Thinking distance + breaking distance
What factors affect thinking distance?
(reaction time)
🟣tiredness
🟣alcohol
🟣drugs
🟣distraction
What factors affect breaking distance?
🟣weather
🟣worn tires
🟣faulty brakes
🟣badly maintained roads
They could decrease friction , increasing distance
what other factors affect thinking distance in general?
- distracted by other people in the car
- eating or drinking
- radio or satellite navigation system
how does speed affect stopping distance?
the larger the speed the larger the breaking distance, the larger the stopping distance
what are the dangers caused by large decelerations?
- car slows down, suddenly the belt exerts a force as you are still moving forwrads, sealbelt force can cause compression injuries
- you would continue moving at high speeds, colliding with dashbaord/seats, causing injury
what forces are involved in typical situation on the road?
F=MA
include the negative signs
what are the speed, accelerations and forces involved in large accerlerations?
- typical motorway speed= 70mph
- force experienced depends of collision time
- things like air bags increase collision time, decreasing the acceleration
What are the three fossil fuels?
⚫️Coal
⛽️Gas
🛢Oil
(All very energy dense)
What are the disadvantages of fossil fuels?
They emit carbon dioxide (greenhouse gases)
They are bad for the environment
They are NON- renewable sources of energy
What is the difference between a renewable source of energy and a non -renewable
Renewable: won’t run out as it is not used up when releasing energy
Non- renewable: will run out as it is used up (takes millions of years to form)
What are some examples of renewable energy sources?
- Solar ( energy from sun light)
- Wind (energy from the wind movement)
- Geothermal (energy from the earth’s heat)
- water high up in dams (hydroelectricity)
- tidal
How do fossil fuel power plants work?
- Fossil fuel is burned
Through this chemical potential energy turns into kinetic energy - The kinetic energy from burning the coal heats up water into steam
- The steam turns the turbine because of pressure
- Turbine turns the generator on
- The generator makes electricity
What are some uses for energy sources?
What is a biofuel?
A renewable fuel that is obtained from the recent living.
Eg: methane gas from sewage, ethanol, sugars,wood.
✅carbon neutral
How are biofuels carbon neutral?
Carbon dioxide is given out when a biofuel is burned however as the plants photosynthesise they take the carbon dioxide back in
what is the difference between an energy store and an energy source?
sources: physical things that you get energy from
fuels: stores energy and must be extracted
How does electricity get sent to your homes?
Power plant —step up transformer—cables/pylons—step down transformer—home (mains/sockets)