REACTION TIMES AND DISTANCES

The purpose of this activity is to look at the effect of different activities on your driving response times, and the distance you travel during those times at different speeds.

A. Measuring reaction time

1. Use the formula d = ½ at² , and solve for t, to find your reaction time when a = 981.2 cm/s².

Distance ruler dropped before I grabbed it (cm)
Trial 1	Trial 2	Trial 3	Trial 4	Trial 5	Average	SDOM

(Show your calculations here)

2. Videotape catching the dropping ruler to determine your reaction time.

Reaction time (s)
Trial 1	Trial 2	Trial 3	Trial 4	Trial 5	Average	SDOM

3. Which method of measuring your reaction time gives you the most precise data? How do you know?

My normal reaction time is _______ seconds.

B. Calculating the distance you travel at different speeds.

1. Determine your reaction time during each situation.
1. For example – your normal (just driving) reaction time is 0.88 seconds. To find your reaction time while receiving a call on your cel phone, multiply your normal reaction time by 1.25.
2. So, 0.88s *1.25 = 1.12s.
3. The directions for calculating each different reaction time are at the top of each data table.

2. Convert each speed (mph) to speed (m/s) by going to http://www.convert-me.com/en/convert/speed.

3. Calculate the distance by multiplying speed (in m/s) x (reaction time for that situation).

4. Convert (the distance traveled in meters) to (the distance traveled in feet) by going to http://www.convert-me.com/en/convert/length.

C. Graph all of your results on one graph using Excel. Please make sure the legend is displayed!

D. Answer the following questions:

a. In general, what happens to the reaction distance as the speed increases?

b. What happens to the reaction distance as the reaction time increases?

For just driving: My reaction time would be (my normal reaction time) = ______.

Description	Speed (mph)	Speed (m/s)	Distance traveled (m)	Distance traveled (ft)
Backing out of the driveway	5
In slow traffic	10
School zone	20
On 33^rd street	30
On Vine street	35
South of town on 183	65
On I-70	70
Speeding on I-70	80
Being stupid	90
Beyond stupidity	120

For receiving a call on the cel phone, my reaction time is (1.25 x my usual reaction time) = ______.

Description	Speed (mph)	Speed (m/s)	Distance traveled (m)	Distance traveled (ft)
Backing out of the driveway	5
In slow traffic	10
School zone	20
On 33^rd street	30
On Vine street	35
South of town on 183	65
On I-70	70
Speeding on I-70	80
Being stupid	90
Beyond stupidity	120

For placing a call on the cel phone, my reaction time is (1.341 x my usual reaction time) = ______.

Description	Speed (mph)	Speed (m/s)	Distance traveled (m)	Distance traveled (ft)
Backing out of the driveway	5
In slow traffic	10
School zone	20
On 33^rd street	30
On Vine street	35
South of town on 183	65
On I-70	70
Speeding on I-70	80
Being stupid	90
Beyond stupidity	120

For talking on the cel phone, my reaction time is (1.073 x my usual reaction time) = _____.

Description	Speed (mph)	Speed (m/s)	Distance traveled (m)	Distance traveled (ft)
Backing out of the driveway	5
In slow traffic	10
School zone	20
On 33^rd street	30
On Vine street	35
South of town on 183	65
On I-70	70
Speeding on I-70	80
Being stupid	90
Beyond stupidity	120

For adjusting the radio/CD player, my reaction time is (1.011 x my usual reaction time) = ______.

Description	Speed (mph)	Speed (m/s)	Distance traveled (m)	Distance traveled (ft)
Backing out of the driveway	5
In slow traffic	10
School zone	20
On 33^rd street	30
On Vine street	35
South of town on 183	65
On I-70	70
Speeding on I-70	80
Being stupid	90
Beyond stupidity	120

For eating/drinking (non-alcoholic) while driving, my reaction time is (1.128 x my usual reaction time) = ______.

Description	Speed (mph)	Speed (m/s)	Distance traveled (m)	Distance traveled (ft)
Backing out of the driveway	5
In slow traffic	10
School zone	20
On 33^rd street	30
On Vine street	35
South of town on 183	65
On I-70	70
Speeding on I-70	80
Being stupid	90
Beyond stupidity	120

*reaction time delays adapted from http://ppc.uiowa.edu/driving-assessment/2001/Summaries/PostSession1/Tokunaga_roberto_abraham.pdf

Remember – these are just the distances you’ll travel BEFORE you hit the brakes!

Next, we’ll deal with acceleration and how long it’ll take your brakes to bring you to a stop.