How much weight can a single strand of hair hold before it snaps? Hair is surprisingly strong. A dry strand can support a load similar to copper wire of the same thickness.
You tie a hair strand to a stand and hang a small hook on the other end. You add weight slowly and record how far the hair stretches at each step. When it breaks, you note the final weight.
Then you compare treated hair to untreated hair. Bleached or permed hair is weaker. Wet hair loses up to 30 percent of its strength. You plot the results on a stretch-versus-weight graph.
Hypothesis
The hypothesis is that treated hair will be weaker than untreated hair.
Hair structure gives each strand surprising strength. A dry strand can support a load similar to copper wire of the same thickness. You can test this by tying a strand to a stand, hanging weights on it, and measuring how far it stretches before it breaks.
A single dry hair strand can support a load similar to copper wire of the same thickness. As you add weight slowly and plot each measurement on a stretch-versus-weight graph, the limits of that strength become clear. Bleached or permed hair reaches those limits sooner than untreated hair. Wet hair loses up to 30 percent of its strength. That drop shows how chemical treatment and moisture both reduce the pulling force hair can handle before it snaps.
Method & Materials
You will tie a strand of hair to a stand, hang weights on the other end, and measure the length of the hair at different weights.
You will need a strand of hair, a stand, a hook, weights, and a ruler.
Eureka Crate — engineering & invention kits for ages 12+ — monthly projects that build real-world skills. (Affiliate link)
The results of this experiment show that treated hair is weaker than untreated hair. Additionally, wet hair is weaker than dry hair.
Why do this project?
This science project is interesting because it allows you to measure the strength of your own hair and compare it to treated hair.
Also Consider
Experiment variations to consider include testing the strength of hair in different humidity levels and testing the strength of hair after different chemical treatments.
Full project details
Additional information and source material for this project are available below.
