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Ball falling in oil

Page history last edited by Joe Redish 7 years, 3 months ago

4.2.2.P8

 

The figure at the right shows the graphs for the position of a small sphere dropped into a long cylinder filled with oil from a few inches above the oil's surface. A number of different times (labeled t0 to t3) are shown on the graphs. 

 

1. At which time does the sphere enter the oil? 

  1. t0
  2. t1
  3. t2
  4. t3
  5. None of them

 

2. At which time does the sphere appear to reach terminal velocity?  

  1. t0
  2. t1
  3. t2
  4. t3
  5. None of them

 

3. At time t3, which best represents all the forces are there acting on the sphere?

  1. The force of gravity and the buoyant force of the oil.
  2. None, since it is moving at a constant velocity.
  3. The force of the sphere's motion.
  4. The resistive force from the oil, gravity, and the buoyant force of the oil.
  5. The resistive and buoyant forces from the oil.
  6. Some other combination of forces.

 

4. If scales for all of these axes were given, what would you need in order to find the net force acting on the object at each instant?

  1. Only the mass of the object.
  2. Only the viscosity and density of the fluid.
  3. Both the viscosity of the fluid and the object's mass.
  4. No additional information is needed. It can be found from the graphs.
  5. Some additional information is needed.

 

5. Explain the reasoning you used to choose each of your answers.

 

 

Joe Redish 12/16/16

  

 

 

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