Every morning on the way to work, driving at or near the posted speed limit, I am passed by cars sprinting five to ten miles per hour faster than I am. Sometimes these people weave in and out of traffic. Sometimes they lay on the horn at me, as if I am the sole cause of their need to hurry.
Putting aside my own level of irritating and conveniently overlooking the fact that some people drive the speed limit just to bug other drivers, I find myself wondering if going five or ten miles per hour over the speed limit really makes a difference. On the other hand, is going those few miles an hour like a sorcerer’s stone going to work a wizardly miracle of arriving on time to work despite leaving my house late?
To find out if wizardry is possible in this case, I turn to the science of physics. The following simple algebraic equation is something every ninth grader who comes through my science class will learn first semester: the speed of a [car] is equal to the distance [the car travels] divided by the time [it takes to reach your destination]. More simply; s=d/t.
But that’s not relevant here. We want to find out if TIME will get less if my speed is faster. Simple. We rearrange the equation getting [the] time [it takes to get somewhere] is equal to [the] distance [you go] divided by [the] speed [you go]. Again, more simply: t=d/s.
To get the results, we simply plug numbers in. We need to establish something here though. I need to know how fast I drive to work. There are nine stoplights and stop signs on my way to the school I teach at; the speed limit also varies over that distance (which remains a constant eight miles.) So I FIRST need to calculate my average speed. To do that, I’ll also tell you that on a usual morning, it take me twenty minutes to get to work. To do this right, I have to say that twenty minutes is 1/3 of an hour. In decimal, that’s .33 of a hour. So, to math:
s= d/t = 8 miles / .33 hours = 25 miles in an hour (or 25 mph). So my AVERAGE speed, stoplights and different speed limits and all is 25 mph. Now we can get down to business!
Let’s say I bump up my speed 5 mph to an average of 30 mph (which means ROUGHLY that in the SPEED LIMIT 30 zone I drive 35 and SPEED LIMIT 35 zone, I drive 40. HOW MUCH TIME WILL I SAVE?
t = d/s = 8 miles / 30 mph = .27 (remember, that’s .27 of an hour, so I have to times it by 60 minutes: .27 x 60 = 16.2 minutes. Speeding 5 mph faster, I magically save 3.8 minutes! WHEW! What a shave! Hmmm…not what I was hoping for.
All right! How about I get serious here? TEN mph faster! Move my average speed up to 40 (consistently 15 mph over the posted speed limit.)
S=d/t=8 mi/ 40 mph = .2 x 60 = 12 minutes! There we go! I’ve saved EIGHT ENTIRE MINUTES OF MY TIME! (Of course, at those speeds, I’m likely to come to the attention of law enforcement authorities eventually and the ticket for speeding might negate some of the financial gain I receive by being to work consistently on time even though I leave late…)
How about greater distances? I used to go to college in
How about REALLY long trips? I must save time there! NYC to LA: 2784 miles. s=d/t=2784 miles/70 mph = 40 hours.
Speed it up to 80 mph: s=d/t=2784/80 = 34.8 hours. I save 5.2 hours. Hmmm…OK, but not really impressive.
Let’s REALLY speed it up to an average speed of 100 mph: s=d/t=2784/100 = (obviously) 27.84 hours. Savings: 12 hours. Half a day. Maybe worth it, but I can’t imagine my Toyota Sienna van maintaining a steady speed of 100 mph. Plus traveling consistently at that speed seems likely to evoke a SMOKEY AND THE BANDIT effect as I pass like a flash from county to county and state to state.
So the only wizardy that happens here is in my mind: I’ve convinced myself that driving a couple miles an hour faster will MAGICALLY and dramatically change the time it takes to get somewhere. I will SWEAR EMPHATICALLY that the above math can’t possibly be true and that I have had personal experience with the wizardry of driving just a little faster, cutting off just a few people and running just a few red lights and stoplights. I KNOW it makes me get to work on time if I leave late!
My only choices are to continue to test the theory until it fits my perceptions, apply to Hogwarts and put on the choosing cap – or slow down and take it easy.