PHYSICS
LAB
Free Fall and Reaction Time
Name ________________________________________
Date ______________________________ Per _______
PARTNER: _______________________________________________________________________________________
Purpose: This activity allows you to use gravitational acceleration to determine your reaction time to a falling object.
Materials: metric ruler
Procedure:
PART A
1. Place your hand on the desktop with your wrist resting on its side and your fingers extending past it (this prevents
you from “chasing” the falling ruler). The gap between thumb and index finger should be approximately 3 cm.
2. Have your partner hold the ruler vertically so that they are holding the top end and the 0 cm mark is even with the
top of your fingers.
3. Your partner should drop the ruler without warning, and you should catch it as quickly as possible.
4. Record the measurement on the ruler at the top edge of your fingers as the distance the ruler fell.
5. Repeat steps 1-5 four more times, and record the measurements in the data table.
6. Calculate the average reaction distance, convert it to METERS, and record it in your data table.
7. Use the free fall equation to determine the reaction time based on that average distance, and record it in the data
table.
PART B
1. Repeat steps 1 and 2 from Part A.
2. Now, CLOSE YOUR EYES. Your partner should drop the ruler with a VERBAL warning, such as “Now!”, and you
should catch it as quickly as possible. The objective is NOT to “trick” your partner, but to compare the
response reactions to visual and auditory stimuli, so be honest!
3. Record the measurement on the ruler at the top edge of your fingers as the distance the ruler fell.
4. Repeat steps 1-5 four more times, and record the measurements in the data table.
5. Calculate the average reaction distance, convert it to METERS, and record it in your data table.
6. Use the free fall equation to determine the reaction time based on that average distance, and record it in the data
table.
DATA TABLE:
Trial 1
Trial 2
Trial 3
Trial 4
Trial 5
Average Distance
PART A (Visual)
PART B (Auditory)
Distance fell
Distance fell
Reaction Time
ANALYSIS:
1. According to the Air Force, reaction times are categorized as:
a. 0.0 s to 0.11 s ‐ good candidate for pilot training
b. 0.11 s to 0.16 s ‐ fair candidate; most likely trained as “back seat”
c. 0.16 s to 0.20 s ‐ preliminary training may improve reaction time; if not, transfer
d. over 0.20 s not even considered
Would you be a good candidate?
2. What is the maximum reading on the ruler you could have and still be a good candidate? (Show your work)
2. What kinds of factors affect your reaction time?
3. Name any possible errors you might have introduced or made during the experiment.
3. 4. Whose reaction time was faster, you or your partners? Try to explain why.