HUMAN REACTION TIME
Learning Objectives
After watching this demonstration, participants should be able to discuss the concept of reaction time
and how it relates to the way people can be injured.
Safety Requirements
Make sure each pair of participants are at least an arm’s length away from other pairs.
Age-Appropriateness
This activity is appropriate for all ages and especially suited to younger participants. With younger
children, “feet per second” is too abstract. Make this concept concrete by having a piece of string or rope
12 feet long. Tell them when the clock ticks, every tick is one second. In one tick, this is how far a corn
stalk rolls is pulled in while using a corn head. Also, younger participants need to know the reasoning of
the tight-fitting clothing, pulled back hair, etc.
The depth of content and the discussion needs to be tailored to the level of understanding of the group.
Refer to the “Teaching Tips” and “Childhood Growth and Development” located in the Teaching Kids
section of the manual.
Suggested Instructors
Extension personnel, FFA and older 4-H members, agricultural equipment dealer personnel, university or
college agriculture faculty, students, practicing farmers, and farm leaders.
Equipment/Supplies
1. Cut 3” X 6” (8 cm X 15 cm) strips of paper or use dollar bills
2. Yardstick or dowel
3. Printed graph for reaction stick
Subject Outline
I. Introduction/Capture Their Attention
A. Introduce yourself and tell about your role teaching farm equipment safety and how it relates to
your session.
B. Share a personal story or experience of someone who has been injured with farm equipment.
C. Invite a person who has had a farm equipment injury to share their experiences. Make sure you
communicate to your guest presenter your lesson plan and time allotment before the day of the
camp. Otherwise, they may talk your entire time and/or children will be so intrigued and ask
many questions.
D. Engage your audience: Ask questions: How many of you help your parents when it is harvest
time? What is your job? Do you know of anyone injured by large equipment? What happened?
II. Activity/Demonstration
A. Ask participants if they think they are really fast. Are you fast enough to get away from danger?
B. Hold a strip of paper between your thumb and index finger of one hand.
C. Hold your thumb and index finger on your other hand on either side of the paper strip halfway
down and about one inch away.
D. Release the paper with one hand and catch it with the other.
E. Tell participants “See how easy it is!”
F. Have students pair up. Have one person in each pair release the paper and the other try
Chapter – Farm Equipment
Human Reaction Time Demonstration – 1 of 2
© Progressive Agriculture Safety Days®
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to catch it. (They won’t be able to catch it very often.)
G. Ask the group how many times out of ten they were successful.
III. Discussion Points
A. Tell participants this was one human against another human. Ask them how they think they
would do against a machine.
B. Show a poster or picture of a combine or auger. Talk about how quickly people could get
pulled into the machine. (Stalk rolls on a corn head pull corn stalks in at 12 feet per second
[3.7 m/sec]. A 6-in [15 cm] auger at 400 RPM entangles at 10 feet per second [3 m/ sec].)
Compare students’ reaction times with the speed of the machines.
C. Discuss the definition of the acronym PTO. (Power Take Offs run other pieces of equipment
at very rapid speeds.)
D. Discuss the resulting injuries from PTO entanglements.
E. Emphasize the importance of following simple safety precautions to prevent entanglement.
1. Wear tight-fitting clothing. No loose string on sweatshirts, baggy sleeves, frayed blue
jeans, or torn coveralls. Tuck in shirt and button sleeves.
2. Keep hair pulled back and close to the head or tucked inside a cap.
3. Replace frayed gloves.
4. Check to make sure all PTO shields and guards are in place.
5. Always make sure the PTO and tractor are shut off and remove the keys before
getting off equipment such as a baler or mower.
6. If using stationary equipment (e.g. auger or silo blower), keep a safe distance from
the PTO. Do not reach over the back of the tractor to adjust the PTO or throttle.
7. Never step over a revolving PTO shaft even if shielded.
8. Always shut off tractor and remove the key before working on the PTO. This will
prevent someone from unintentionally putting the PTO in gear.
9. Never let anyone under 18 operate a PTO. Keep children away from stationary
PTO equipment (e.g., grinders or augers).
10. Make PTO work areas off limits to young children.
F. Discuss reaction time with participants, emphasizing that people cannot react fast
enough to avoid injury (and sometimes death) in dangerous situations.
Chapter – Farm Equipment
Human Reaction Time Demonstration – 2 of 2
© Progressive Agriculture Safety Days®
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SPEED CHARTS
PTO Shaft (540)
FKeep all shields in place.
FClothing should be free of loose ends that might entangle.
FStay clear of moving parts.
PTO at 540 RPM - pulls in 7 feet per second (2.1 m/sec)
2.1 feet in 0.30 seconds(0.6 meters in 0.30 seconds)
2.8 feet in 0.40 seconds(0.9 meters in 0.40 seconds)
3.5 feet in 0.50 seconds(1.1 meters in 0.50 seconds)
4.2 feet in 0.60 seconds(1.3 meters in 0.60 seconds)
PTO Shaft (1000)
FKeep all shields in place.
F Clothing should be free of loose ends that might entangle.
F Stay clear of moving parts.
PTO at 1000 RPM - pulls in 13 feet per second (4 m/sec)
2.6 feet in 0.20 seconds(0.8 meters in 0.20 seconds)
3.9 feet in 0.30 seconds(1.2 meters in 0.30 seconds)
5.2 feet in 0.40 seconds(1.6 meters in 0.40 seconds)
6.5 feet in 0.50 seconds(2.0 meters in 0.50 seconds)
7.8 feet in 0.60 seconds(2.4 meters in 0.60 seconds)
Chapter - Miscellaneous
Speed Charts – 1 of 4
speed charts
1.4 feet in 0.20 seconds(0.4 meters in 0.20 seconds)
Auger Entanglement
FStay clear of all moving parts.
FKeep all shields in place.
A 6-inch (15 cm) auger at 400 RPM entangles at 10 feet per second (3
m/sec)
2 feet in 0.20 seconds (0.6 meters in 0.20 seconds)
3 feet in 0.30 seconds (0.9 meters in 0.30 seconds)
Speed Charts
4 feet in 0.40 seconds (1.2 meters in 0.40 seconds)
5 feet in 0.50 seconds (1.5 meters in 0.50 seconds)
6 feet in 0.60 seconds (1.8 meters in 0.60 seconds)
Rotary Lawn Mower
FKeep hands and feet away from blade area.
FDisengage power, turn off engine, wait for blade to stop before doing
any maintenance.
FLook behind you before backing up.
FKeep all shields in place.
Rotary lawn mower has 52 cuts per second
10 cuts in 0.20 seconds
15 cuts in 0.30 seconds
20 cuts in 0.40 seconds
26 cuts in 0.50 seconds
31 cuts in 0.60 seconds
Speed Charts – 2 of 4
Chapter - Miscellaneous
Stalk Rolls On Corn Head
FDisengage power and turn off engine before attempting to unplug.
Corn head pulls corn stalks in at 12 feet per second (3.7 m/sec)
2.4 feet in 0.20 seconds(0.7 meters in 0.20 seconds)
3.6 feet in 0.30 seconds(1.1 meters in 0.30 seconds)
4.8 feet in 0.40 seconds(1.5 meters in 0.40 seconds)
6.0 feet in 0.50 seconds(1.8 meters in 0.50 seconds)
Belt and Pulley
FKeep all shields in place.
FDisengage power and turn off engine before doing any maintenance.
Belt and pulley travel at 66 feet per second (20 m/sec)
13 feet in 0.20 seconds (3.9 meters in 0.20 seconds)
19 feet in 0.30 seconds (5.8 meters in 0.30 seconds)
26 feet in 0.40 seconds (7.9 meters in 0.40 seconds)
33 feet in 0.50 seconds (10 meters in 0.50 seconds)
39 feet in 0.60 seconds (11.9 meters in 0.60 seconds)
Chapter - Miscellaneous
Speed Charts – 3 of 4
speed charts
7.2 feet in 0.60 seconds(2.2 meters in 0.60 seconds)
Distance Equipment Falls During Reaction Time
FMechanically lock and block-up equipment.
FUse approved lifting equipment.
An object falls at a rate of 32 feet per second per second (9.8 m/sec/
sec)
0.6 feet in 0.20 seconds(0.2 meters in 0.20 seconds)
Speed Charts
1.4 feet in 0.30 seconds(0.4 meters in 0.30 seconds)
2.5 feet in 0.40 seconds(0.8 meters in 0.40 seconds)
4.0 feet in 0.50 seconds(1.2 meters in 0.50 seconds)
5.7 feet in 0.60 seconds(1.7 meters in 0.60 seconds)
Speed Charts – 4 of 4
Chapter - Miscellaneous
Chapter - Miscellaneous
How Quick Are You? – 1 of 2
How Quick Are You? – 2 of 2
Chapter - Miscellaneous