Data & Trends
This is the main "puzzling pattern" the class is investigating: Overall traffic deaths have decreased since the 90s, but this specific statistic has actually been trending upward since around 2010.
What are vehicle collisions (or crashes/injuries)?
According to research, distracted driving has this specific numerical effect on a driver’s reaction time.
What is doubling it?
On a position-time graph, a steeper slope indicates that the vehicle is doing this.
What is moving faster/higher speed?
If you double the mass or the initial speed of a car, the stopping time does this.
t=(m×v)/F
What is doubles?
This is the formal name given to the physics principle that F=ma.
What is Newton’s Second Law of Motion?
National data shows that while people inside vehicles are generally safer, there has been a steep and concerning rise in fatalities for this group of people, which includes pedestrians and cyclists.
Who are non-occupants?
This is the distance a vehicle travels between the moment an obstacle appears and the moment the driver hits the brakes.
What is reaction distance?
On a position-time graph, a completely flat, horizontal line indicates the car is in this state.
What is stopped/at rest?
If you double the braking force, the stopping time does this.
t=(m×v)/F
What is cut in half/halved?
According to the updated M-E-F triangle, these specifically "cause a change in motion."
What are unbalanced forces?
These are the three components of the consensus model triangle used to organize all physics ideas.
M-E-F
What are Matter, Energy, and Forces?
This is the distance a vehicle travels from the moment the brakes are applied until the vehicle comes to a complete stop.
What is braking distance?
On a speed-time graph, the slope of the line represents this specific physical quantity.
What is acceleration?
According to the stopping equation (t=mv/F), if a delivery truck has three times the mass of a small car but uses the same braking force and speed, its stopping time will change in this specific way.
What is tripling (or taking 3 times as long to stop)?
Using the formula a=F/m, calculate the acceleration of a 1,000 kg car being slowed by a 5,000 N braking force.
What is 5m/s2?
Data shows this specific technology was introduced in 2007 and correlates with the rise in crashes after 2010.
What is the smartphone/iPhone?
If a car's speed increases, this factor stays exactly the same, even though the car travels further before the brakes are hit.
How long it takes you to respond to a stimuli.
What is reaction time?
This Greek symbol (Δ) is used by scientists to represent a "change in" a variable.
What is Delta?
Driving on a wet road is dangerous because the reduction in road friction causes a decrease in this specific variable.
What is braking force?
Using the stopping equation, calculate the braking force needed to stop a 2,000 kg car going 20 m/s in exactly 2 seconds.
t=(m×v)/F
What is 20,000 N?
This term describes when two variables change in the same way over time, even if one does not necessarily cause the other. Not causation.
What is correlation?
In engineering design, this is a limitation or requirement you must consider, such as cost or how a safety feature affects people differently.
What is a constraint?
This is what a downward-sloping (negative) line on a speed-time graph tells you about the car's motion.
What is slowing down/decelerating?
Imagine a car is traveling at twice its normal speed on a rainy day where the braking force is cut in half. According to the mathematical model, the stopping time for this car will be this many times longer than usual.
What is 4 times longer? (Note for teacher: Logic is t=(m×2v)/(0.5F), which equals 4× the original time).
This is the definition of acceleration expressed in terms of a speed-time graph.
What is the change in speed divided by the change in time?