Physics · Bernoulli's principle and its applications

The working principle of a ball point pen is:

The working principle of a ball point pen is:

  • A. Bernoullis theorem
  • B. Surface tension
  • C. Gravity
  • D. Viscosity

Step-by-step solution

A ballpoint pen works by using a tiny ball bearing that rotates as the pen moves, transferring ink from the cartridge to the paper. The ink is highly viscous, which prevents it from leaking when the pen is not in use and allows it to be picked up by the ball. The ball's rotation shears the ink, reducing its viscosity temporarily so it flows smoothly. Among the options, viscosity is the key principle.
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