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Question
The speed of propagation of the action potential (an electrical signal) in a nerve cell depends (inversely) on the diameter of the axon (nerve fiber). If the nerve cell connecting the spinal cord to your feet is 1.1 m long, and the nerve impulse speed is 18 m/s, how long does it take for the nerve signal to travel this distance?
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Final Answer
$61 \textrm{ ms}$
Solution Video

OpenStax College Physics Solution, Chapter 2, Problem 12 (Problems & Exercises) (0:45)

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Video Transcript

This is College Physics Answers with Shaun Dychko. A nerve connecting your spinal cord to your feet is 1.1 meters long and the signal that travels along that nerve goes at a speed of 18 meters per second on average. So the question is how long will it take for the signal to go from the spinal cord to the feet? So average speed is distance divided by time and we can rearrange this to solve for <i>t</i> by multiplying both sides by <i>t</i> over <i>v avg</i> and then we have <i>t</i> is the distance divided by the average speed. So that's 1.1 meters divided by 18 meters per second which works out to 61 milliseconds.