- #1

Est120

- 54

- 3

- Homework Statement
- compute the drag force on the sphere in dynes

- Relevant Equations
- weight of fluid displaced= rho*4/3pi*R^3

weight of hollow sphere= mg

i tried a force balance around the sphere but the weight of the displaced fluid is greater than the weight of the sphere which gives a net acceleration upwards and no terminal velocity but the book says that the terminal velocity has a certain value from there the exercise is meaningless to me

i Attach a photo of the solution where the numerical answer comes from, but as I told you, I no longer understood why a terminal velocity is reached if the Archimedean force is always constant and the weight of the sphere is also constant , so adding a force due to the resistance around the liquid would only accelerate the sphere upwards and it would never reach a constant terminal velocity in downwards direction. the book is Bird's Transporth phenomena page 193

i Attach a photo of the solution where the numerical answer comes from, but as I told you, I no longer understood why a terminal velocity is reached if the Archimedean force is always constant and the weight of the sphere is also constant , so adding a force due to the resistance around the liquid would only accelerate the sphere upwards and it would never reach a constant terminal velocity in downwards direction. the book is Bird's Transporth phenomena page 193