Stopping distances and reaction time Flashcards
(15 cards)
Equation linking braking distance, stopping distance, and thinking distance
Stopping= thinking + braking
Stopping distance = … +…
Thinking distance + braking distance
What is an emergency stop
Where maximum force is applied by the brakes in order to stop the car in the shortest possible distance
What is stopping distance
The distance it takes to stop a car in an emergency
What is thinking distance
How far the car travels during the drivers reaction time/ time between seeing a hazard and applying the brakes
What is braking distance
Distance taken to stop under the braking force
What is a typical cats braking distance at
30mph: …m
60mph: …m
70mph: …m
30mph: 14m
60mph: 55m
70mph: 75m
What is thinking distance affected by
-s…
-r… t…
-your speed
-your reaction time
What is braking distance affected by
-s…
-w… eg wet or s…
-r… s… eg i…
-c… of t…
-b… c…
-speed
-weather eg wet or snowy
-road surface eg icy
-condition of tyres
-brake condition
Do speed limits affect stopping distance
Yes, the faster you are going the more stopping distance is needed
How do brakes work
-when the p… is pushed this causes brake p… to be p… onto the w…
-this contact causes f… which causes w… to be done
-the work done t… energy from the … energy store of the w… to the t… energy store of the brakes
-the b… increase in t…
-when the pedal is pushed this causes brake pads to be pressed onto the wheels
-this contact causes friction which causes work to be done
-the work done transfers energy from the kinetic energy store of the wheel to the thermal energy store of the brakes
-the brakes increase in temperature
Why is a greater braking force needed with speed
-the faster a vehicle is going the more energy it has in its kinetic stores so more work needs to be done to stop it
What can reaction time be affected by
-t…
-d…
-a…
-d…
-tiredness
-drugs
-alcohol
-distractions
Reaction time practical
Ruler drop test
1. Sit with a… resting on the e… of the table, and get someone to hold a r… so that it hangs between your t… and forefinger, lined up with …
2. With no w… randomly drop the ruler, the other person should try and c… their fingers as q… as possible to stop it
3. Record the m… of the ruler, the longer the d… the longer the r… time
5. Use the equation …-u2 =… to find the v…, then 🔺v=… to find the r… time
4. R… the experiment s… times and calculate a m… reaction time
Ruler drop test
1. Sit with arm resting on the edge of the table, and get someone to hold a ruler so that it hangs between your thumb and forefinger, lined up with 0
2. With no warning randomly drop the ruler, the other person should try and close their fingers as quickly as possible to stop it
3. Record the measurement of the ruler, the longer the distance the longer the reaction time
5. Use the equation v2-u2 =2as to velocity, then 🔺v=at to find the reaction time
4. Repeat the experiment several times and calculate a mean reaction time
How does speed affect braking distance more than thinking distance
-as a car s… up the t… distance increases at the same r… as the speed
-this is because the t… time stays pretty c…
-braking d… however i… faster the more you s… up as the w… done needed to stop the c… is equal to the cars k… energy …
-as a car speeds up the thinking distance increases at the same rate as the speed
-this is because the thinking time stays pretty constant
-braking distance however increases faster the more you speed up as the work done needed to stop the car is equal to the cars kinetic energy store
