Purpose
To derive and use a uniform linear acceleration equation to measure human reaction time.
Concept
An object dropped from rest initially falls with uniform linear acceleration.
The relationship between the time an object falls and the distance it has fallen can be given by
Materials
Meter stick
Procedure Person A
1. Hold a meter stick so that the 50.0 cm mark is in between the open fingers of a classmate. Have the classmate grasp the meter stick as soon as he/she sees it begin to fall.
2. Release the meter stick and record the point that the classmate is holding the meter stick.
3. Repeat for a total of 5 trials.
Person B
1. Repeat the experiment with another classmate.
Observations and Data: Person A
Initial y (cm)
Final y (cm)
Change in y (cm)
g (m/s^2)
Reaction time t (s)
50.0
9.80
50.0
9.80
50.0
9.80
50.0
9.80
50.0
9.80
Person B
Initial y (cm)
Final y (cm)
Change in y (cm)
g (m/s^2)
Reaction time t (s)
50.0
9.80
50.0
9.80
50.0
9.80
50.0
9.80
50.0
9.80
Analysis
1. Solve the uniform linear acceleration equation for time.
2. Use the uniform linear acceleration equation to calculate the reaction time for each trial.
3. Calculate the average reaction time for each person. Which person had the shorter average reaction time?
4. What are some of the factors for human reaction time?
Application
If person A, from the experiment, was piloting an airplane at 168 m/s how far
would he/she travel before being able to react to a bird in front of the plane?