Video Transcript
If a fluid increases in viscosity,
in which of the following ways does this change the fluid’s resistance to
deformation? (a) The fluid has less resistance
to deformation. (b) The fluid has greater
resistance to deformation. (c) The resistance of the fluid to
deformation is not affected.
To get started here, let’s imagine
some fluid that increases in its viscosity. So, how about this? Say that we have a container that’s
filled with honey. We know that honey is already a
fairly viscous or thick fluid. And let’s say that we decrease the
temperature of this honey. We cool it down so that it gets
even thicker. By cooling the honey then, we’re
increasing the viscosity of this fluid. We want to know how this changes
our fluid’s resistance to deformation.
And we can recall that deformation
refers to a change in the flow of a fluid. One way we could change the flow of
this fluid, that is, deform it, is by mixing it, say, with a spoon. So, here’s the question: how does
the honey’s resistance to the spoon’s movement through it change as the honey’s
viscosity increases?
We know from experience that for a
thicker, that is, more viscous fluid, the resistance to a change in flow, that is,
the resistance to deformation, will increase. Simply speaking, it’s harder to
stir a thicker or more viscous fluid. And we see that of our three answer
options, option (b) describes this case. This tells us that as the viscosity
of our fluid increases, so does the fluid’s resistance to deformation.
