Topic 1: What is a Fluid?

What is a fluid?

• A substance that can flow and take the shape of its container

• A substance with a definite shape that cannot flow

• A solid material that can be broken into pieces

• A material that cannot change shape

Answer explanation

A fluid is defined as a substance that can flow and take the shape of its container, distinguishing it from solids, which have a definite shape and cannot flow.

Fluids take the shape of their container because they spread out and flow, while solids do not because they have (a)   that hold a definite shape.

• Fluids have particles that are pack
• Fluids spread out and flow, while s
• Solids flow just like fluids but ar
• Fluids and solids behave the same w

Answer explanation

Fluids spread out and flow because their particles are not tightly packed, allowing them to take the shape of their container. In contrast, solids have tightly packed particles that maintain a definite shape.

Match the following scenarios with their outcomes regarding the volume and shape of water:

• Keeping water in the same container without any movement.

• The volume will decrease, and the shape will change.

• Pouring water from a cup into a bowl.

• The water will turn into a solid when poured into the bowl.

• Freezing water in a freezer.

• The volume will stay the same, but the shape will change to fit the bowl.

• Transferring water from one container to another without changing its state.

• The volume and shape will both stay the same.

Answer explanation

When you pour 200 mL of water into a bowl, the volume remains constant at 200 mL, but the shape changes to conform to the shape of the bowl, as liquids take the shape of their container.

Why is helium, a gas, considered a fluid?

• Because it has a definite shape

• Because it takes up space in a container and flows to fill the available space

• Because it can be poured from one container to another

• Because it behaves like a solid in certain conditions

Answer explanation

Helium is considered a fluid because it takes up space in a container and flows to fill the available space, similar to liquids. This property distinguishes fluids from solids, which have a definite shape.

Critical Thinking: Imagine you have a substance that flows very slowly, such as honey. Based on the definition of a fluid, should honey be considered a fluid? Why or why not?

Answer explanation

Yes, honey should be considered a fluid because it can flow and take the shape of its container, despite its slow flow rate. Fluids are defined by their ability to deform under stress, not by their speed of flow.

Anaya and Daniel are organizing a science experiment. Write your own examples of fluids and non-fluids in the spaces provided to help them with their project.

Answer explanation

Fluids are substances that flow, like water and oil. Non-fluids are rigid and do not flow, such as wood and metal. This distinction helps categorize materials based on their physical properties.

(a)   is an example of a fluid.

• Ice
• Water
• Iron
• Wood

Match the following properties with the correct characteristic of fluids.

• Characteristic of solids

• They have a fixed volume

• Characteristic of gases

• They have a definite shape

• Characteristic of solids

• They can be compressed easily

• Characteristic of fluids

• They can flow and take the shape of their container

Why is water considered a fluid?

• Because it is solid at room temperature

• Because it can flow and take the shape of its container

• Because it has a definite shape

• Because it cannot be compressed

What characteristic defines a fluid?

• It has a fixed volume and shape

• It can flow and adapt to the shape of its container

• It is always gaseous

• It cannot be compressed