The neurons of giant squids, for example, consist of axons with very large radii, which allows the squid to react very quickly when confronted with a predator. Assuming no change in the resistivities or membrane thickness of the axon, by what factor must the radius of the axon increase such that the speed of the pulse increases by a factor of 10

100

Explanation:

= Resistivity of axon

r = Radius of axon

t = Thickness of the membrane

= Resistivity of the axoplasm

Speed of pulse is given by

So, radius is given by

If radius is increased by a factor of 10 new radius will be

So, The radius will increase by a factor of 100.

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.