I had a science lab and we had to place a loop of thread in a bucket of water and in the middle of the thread we had to drop a drop of soap in the water. Immediatley the thread straightened and was pushed to the outside of the bucket. Why did this happen? Why would soap make that happen? The type of soap was dishwashing soap so you know. Please help!!!
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Firstly oil/soap and water don't mix, they never combine. So when you drop the soap into the water the soap forms a kind of membrane and expands to fill the space, pushing the thread to the sides of the bucket.
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Soap breaks the surface tension of the water. That's why soap helps get dirt off because without the surface tension the water can get into crevices it can't get into otherwise.