Variations in Viscosity

Question 1

what is the viscosity of a fluid primarily dependent on

Answer 1

temperature

Question 2

how does a change in temperature change the viscosity of a fluid

Answer 2

an increase in the temperature results in a decrease in the viscosity of the fluid

Question 3

why does an increase in temperature decrease velocity

Answer 3

• when its temperature increases its internal energy (kinetic and potential energy) also increases
• an increased kinetic energy means that its particles have a larger vibrational amplitude, therefore increasing the space between them
• this leads to the adhesive forces between molecules decreasing
• therefore reducing the viscosity

Question 4

how is this idea of fluids getting runnier in warmer conditions used in lubricating oils for cars

Answer 4

• the oil gets hotter when the mechanical parts move past each other
• this causes the viscosity of the oil to reduce
• leading to the frictional forces between the moving parts getting smaller and reducing wear

Question 5

for other fluids like molten chocolate, what other factor can impact the viscosity of it

Answer 5

the rate of flow of the liquid

Question 6

what is the relationship between the rate of flow and the viscosity of a liquid

Answer 6

an increase in the rate of flow leads to an decrease in viscosity

Question 7

what is this property an example of

Answer 7

thixotropy

Question 8

what actions can affect thixotropic substances and what is an example of how

Answer 8

• stirring or vibrating
• such as drip-dry paint becoming runny when stirred or applied to a surface
• but not when they are held on the brush