Question

Proteins in motion. Among the smallest forces biophysicists measure result from motor proteins that move molecules within cells. The protein kinesin exerts a force of 6.0 pN (6.0 ×10?12N).

1.What magnitude of acceleration could it give a molecular complex with mass 3.5

×10?18kg? (Drag forces dominate within the cell, so accelerations last only briefly before terminal speed is reached.)

Muscles are attached to bones by elastic bundles called tendons. For small stretches, tendons can be modeled as springs obeying Hooke's law. Experiments on the Achilles tendon found that it stretched 2.66 mm with a 125-kg mass hung from it.

1.By how much would it have to stretch to store 46.3

J of energy?

Answer 1