Why it hurts when someone pulls his hair but not when he goes for a haircut? Why a cotton garment cannot keep us as warm in winter as a woollen sweater can?

cbse
cbse-class-7-science
fibre-to-fabric

#1
  • Why it hurts when someone pulls his hair but not when he goes for a haircut?
  • Why a cotton garment cannot keep us as warm in winter as a woollen sweater can?

Answer:

  • Hair is made up of proteins, which are dead cells. They are attached to the scalp with living cells, from where they grow. So, while getting a haircut a person does not feel pain because dead cells are being cut, but when it is pulled from scalp the living cells are also being pulled along.
  • Woollen sweater traps air in between whereas cotton allows the air to pass through it. Air being a bad conductor of heat does not let body heat to escape beyond the sweater. Therefore, it is much warmer.