Motion of a sphere in a liquid

In summary, the conversation discusses the concept of terminal velocity and the role of different forces in determining the direction of motion. The speaker proposes a solution to a problem involving determining the weight, buoyant force, and drag force of an object. However, they are confused by the idea of the drag force acting downwards when the buoyant force is greater than the weight. They then correct themselves and state that the sphere is actually going up instead of down, as the buoyant force is larger than the weight.
  • #1
Est120
51
3
Homework Statement
determine the drag force
Relevant Equations
Archimedes principle formula, weight formula
in my head this is just a silly problem in which i need to determine the ↓ force (weight) and the ↑force (archimedes bouyant force) and then the difference must be the drag force ↑ (the force that involves velocity) but i can't get any sense out of this answer
how is possible for the sphere to reach terminal velocity (and thus keep falling) if the bouyant force is greater in magnitude than the weight?
how is the drag force acting downwards (in the direction of motion) ? this doesn't make any sense to me
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  • #2
i think the sphere must be going up instead of down so this actually makes sense
 
  • #3
It Is going up. The buoyant force Is larger than the Wright.
 

1. What is the motion of a sphere in a liquid?

The motion of a sphere in a liquid is a result of the interaction between the sphere and the surrounding liquid. It can be affected by various factors such as the density of the liquid, the size and shape of the sphere, and the viscosity of the liquid.

2. How does the density of the liquid affect the motion of a sphere?

The density of the liquid affects the motion of a sphere by creating a buoyant force that opposes the weight of the sphere. This buoyant force can either slow down or speed up the motion of the sphere depending on the density of the liquid and the density of the sphere.

3. What is the role of viscosity in the motion of a sphere in a liquid?

Viscosity is the measure of a liquid's resistance to flow. In the motion of a sphere in a liquid, viscosity plays a crucial role in determining the speed and direction of the sphere's motion. A more viscous liquid will result in a slower and more turbulent motion of the sphere, while a less viscous liquid will allow for a faster and smoother motion.

4. How does the size and shape of the sphere affect its motion in a liquid?

The size and shape of the sphere can greatly impact its motion in a liquid. A larger sphere will experience more resistance and therefore have a slower motion compared to a smaller sphere. The shape of the sphere can also affect its motion, with more streamlined shapes experiencing less resistance and having a faster motion.

5. What is the significance of the Reynolds number in the motion of a sphere in a liquid?

The Reynolds number is a dimensionless quantity that represents the ratio of inertial forces to viscous forces in a fluid flow. In the motion of a sphere in a liquid, the Reynolds number determines whether the flow is laminar or turbulent. A low Reynolds number indicates a laminar flow, while a high Reynolds number indicates a turbulent flow. This can greatly affect the motion of the sphere and the forces acting upon it.

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