## Question

which object will sink in freshwater, which has a density of 1.0 g/cm3?

- Object 1, which has a density of .08 g/cm3
- Object 2, which has a density of 1.9 g/cm3
- Object 3, which has a density of .06 g/cm3
- Object 4, which has a density of .03 g/cm3

### Final Answer

In a freshwater, an object will sink if its density is greater than the density of water (1.0 g/cm³). Therefore, Object 2 with a density of 1.9 g/cm³ will sink. Objects 1, 3, and 4 will float as their densities are less than that of water.

### Explanation

**Data:**

Density of freshwater = 1.0 g/cm³

First Object: Density = 0.08 g/cm³

Second Object: Density = 1.9 g/cm³

Third Object: Density = 0.06 g/cm³

Fourth Object: Density = 0.03 g/cm³

According to the floatation principle, an object will sink in a fluid (like freshwater) if its density is greater than the density of the fluid. Conversely, it will float if its density is less than the density of the fluid.

**Solution:**

- Object 1 has a density of 0.08 g/cm³, which is less than the density of freshwater (1.0 g/cm³). Therefore, Object 1 will float.
- Object 2 has a density of 1.9 g/cm³, which is greater than the density of freshwater (1.0 g/cm³). Hence, Object 2 will sink.
- Object 3 with a density of 0.06 g/cm³ has a density less than that of freshwater. Therefore, it’s also safe to say that Object 3 will float.
- Object 4 has a density of 0.03 g/cm³, which is less than the density of freshwater. Therefore, Object 4 will also float.

Therefore, Object 2 will sink in freshwater, while Objects 1, 3, and 4 will float.

I want you to imagine you are in a pool, and you are trying to push a beach ball underwater. The force pushing it up is called upthrust. Objects float when the upthrust is equal to their weight. Now, if something is heavy (high density), it sinks because the upthrust isn’t strong enough to balance its weight in the water. So, things like rocks sink, but light objects, like a rubber duck, float because upthrust can easily support their weight in water.

#### Physics Equations Behind our Answer

The equation for density is **ρ**=m/v. In the case of the fresh water and the four objects, we are dealing with the ratio of the mass to their volume. Additionally, there is also a force that is pushing the object upward and it’s called upthrust.

Upthrust, is also known as buoyant force. It is the force that pushes an object upward when it’s placed in a fluid (like water or air). This force opposes the weight of the object and depends on the volume of the object displaced in the fluid. When upthrust is greater than or equal to the weight of the object, it floats; otherwise, it sinks. This is why some objects float in water—they experience an upward force that helps counteract their weight.

The equation for upthrust (buoyant force) is given by Archimedes’ principle:

F_{up}=ρ⋅g⋅V_{dis}

where:

- F
_{up }is the upthrust or buoyant force, - ρ is the density of the fluid (liquid or gas) the object is in,
- g is the acceleration due to gravity,
- V
_{dis}is the volume of the fluid displaced by the submerged part of the object.

This equation helps us to understand how much force is pushing upward on an object submerged in a fluid, determining whether the object will float or sink.

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