Measuring Human Reaction Time with a Ruler

[Dgolverk]

Hello,
I need some help figuring out how to proceed.

Homework Statement

Make up a ruler, that can measure human reaction time in time intervals of 0.05s. There supposed to be 6 intervals in total.
We did a similar experiment in class, where a student drops a ruler and I need to catch it as fast as I can. The displacement (cm as shown on the ruler) was 17cm.

The Attempt at a Solution

I used a uniform acceleration equation: displacement = (Initial Velocity)(change in time) + 1/2(Acceleration due gravity)(change in time)^2
and found the time to be 0.18s for the 17 cm.

So now I need to make a ruler that will calculate time instead of displacement.
However I don't know what values to use every 0.05s on the ruler.

 

[Nate810]

I know the final time is 0.18s but I don't know what the initial time is to start off the ruler. Can anyone help me out? Thanks a lot! The equation you used is fine for finding the time taken for the object to fall 17 cm. However, to make your ruler, you will need to find the displacement (or distance) at regular intervals of 0.05s. To do this, you could use the same equation with changing times. Let's start with the first interval, from 0 s to 0.05s. The initial velocity is 0, and the acceleration due to gravity is -9.8 m/s2. Therefore, the displacement in this interval would be 0.5 x (-9.8)(0.05)^2 = -0.00245m, or 2.45 mm. You can then repeat this process for each interval and fill in the displacements on your ruler. For example, for the second interval, from 0.05s to 0.1s, the displacement would be 0.5 x (-9.8)(0.1)^2 = -0.00980m, or 9.8 mm. Once you have the displacements for each interval, you can convert them into time values by solving the equation you used earlier (displacement = (Initial Velocity)(change in time) + 1/2(Acceleration due gravity)(change in time)^2). This should give you the time taken for each interval, which you can then use to make up your ruler.

 

[Moetasim]

I would suggest using a stopwatch or a digital timer to measure human reaction time instead of a ruler. While a ruler can be a useful tool for measuring displacement, it is not accurate enough to measure time intervals of 0.05s. Additionally, a ruler is dependent on the person dropping it and the person catching it, which can introduce human error into the experiment.

To measure human reaction time accurately, you can use a simple reaction time test where a stimulus, such as a sound or a visual cue, is presented and the person must respond as quickly as possible. The time between the stimulus and the response can be measured using a stopwatch or a digital timer.

If you would still like to use a ruler for this experiment, you can try marking the ruler at specific intervals, such as every 0.05s, and have the subject catch the ruler at the marked intervals. However, this method may not be as accurate as using a stopwatch or digital timer.

In conclusion, using a ruler to measure human reaction time may not provide the most accurate results. It is important to use appropriate tools and methods when conducting scientific experiments to ensure reliable and valid data.