Flow Rate and Viscosity Why do certain fluids flow faster than others?

Flow Rate Have you ever tried to pour ketchup out of a brand-new bottle? It takes a lot of force to start the ketchup flowing. Very little force is needed to start maple syrup flowing. That’s because maple syrup is much thinner and has less resistance to flowing than ketchup. Oil has a larger viscosity than water, therefore oil has a slower flow rate.

Flow Rate Not all fluids have the same flow rate. We can describe how quickly fluids move using the term “flow rate.” Flow rate measures the volume of a fluid that moves past a certain point in a given amount of time. Imagine your kitchen tap takes 4 seconds to fill up a 1 litre container of water. The flow rate from the tap is 1l 4s If you turn on the tap only half way, the flow rate will decrease. = 0.25L/s

The Effect of Temperature on Viscosity Temperature effects the viscosity of materials: Liquids Heated - viscosity decreases Cooled - viscosity increases Gases Heated - viscosity increases Cooled - viscosity decreases

The Effect of Temperature on Viscosity

Flow Rate Several factors affect flow rate, including: The type of fluid The force pushing on the fluid The size of the pipe or opening the fluid is flowing through The surface the fluid is flowing over Test this theory: Take a type of fluid and pour it over 3 different surfaces and see if the flow rate changes.

Adhesion and Cohesion Adhesion and cohesion affect the flow rate of liquids. Adhesion is the attraction of two different objects or fluids to each other (Example: water drops in a glass) Cohesion is the strength with which the particles of an object or fluid attract each other Surface tension is the property of a liquid in which the surface of the liquid acts as a thin skin due to cohesion. The positive and negative parts of the water molecule are attracted to each other (cohesion)

Viscosity A fluid’s viscosity is its “thickness”, or its resistance to flow. Viscosity is a measure of how easily a fluid’s particles can slide past one another.

 Check Your Thinking Molasses has a high viscosity. Explain what this statement means. How does the thickness of a fluid compare to its viscosity? Give an example.