- #1
kasse
- 384
- 1
I understand the explanation of tios problem, except the fact that the force acting upwards bacause of surface pressure is [tex]2 \pi r \gamma_{WG} cos(180 - \theta)[/tex]. Why is that?
Surface Pressure: Exploring the Force of 2πrγWGcos(180-θ)
In summary, the conversation discusses the forces at play when an object is placed on the surface of water. The upward force of surface pressure is determined by the formula 2 \pi r \gamma_{WG} cos(180 - \theta), while the downward forces are the weight of the object and the buoyancy force. The surface tension acts tangentially, and the water pressure acts normal to the surface. It is noted that a steel blade will float on the surface of water, but will sink if placed deeper in the water. The person expresses gratitude for the helpful information provided.
I understand the explanation of tios problem, except the fact that the force acting upwards bacause of surface pressure is [tex]2 \pi r \gamma_{WG} cos(180 - \theta)[/tex]. Why is that?
- #2
Astronuc
Staff Emeritus
Science Advisor
2023 Award
- 21,910
- 6,335
There is the bouyancy force and the surface tension. The water pressure acts normal to the surface, but surface tension acts tangentially. Weight of course acts downward with gravity, and to balance the forces, on is concerned with the components of pressure and surface tension acting vertically.
- #3
yohan75
- 1
- 0
A steel blade placed gently on the surface of water floats on it. If the same blade is kept well inside the water it sinks. Can you people please explain why? Thanks for the lot of info that you post. It is really of great help.
1. What is surface pressure?
Surface pressure is a measure of the force exerted by a fluid, such as air or water, on a surface. It is typically measured in units of force per unit area, such as pounds per square inch (psi) or pascals (Pa).
2. What does 2πrγWGcos(180-θ) represent in the formula for surface pressure?
In this formula, 2πr represents the circumference of the surface, γ represents the surface tension of the fluid, W represents the weight of the fluid above the surface, G represents the acceleration due to gravity, and θ represents the contact angle between the surface and the fluid.
3. How does surface tension affect surface pressure?
Surface tension is a measure of the cohesive forces between molecules at the surface of a fluid. This cohesive force contributes to the force exerted by the fluid on a surface, therefore, a higher surface tension will result in a higher surface pressure.
4. Is surface pressure a constant value?
No, surface pressure is not a constant value. It can vary based on factors such as the properties of the fluid, the shape and size of the surface, and the surrounding environment.
5. How can surface pressure be measured?
Surface pressure can be measured using a variety of instruments such as a pressure sensor, a manometer, or a tensiometer. These instruments can provide accurate measurements of the force exerted by a fluid on a surface.
Similar threads
-
Introductory Physics Homework Help
-
Advanced Physics Homework Help
-
Advanced Physics Homework Help
-
Advanced Physics Homework Help
-
Advanced Physics Homework Help
-
Mechanics
-
Advanced Physics Homework Help
-
Introductory Physics Homework Help
-
Advanced Physics Homework Help
-
Mechanical Engineering