The water cooler

The water cooler

Pencil and paper
Overview
Connecting to the Curriculum
Marking Student Responses
This task is about the surface of water on a moving train.

Nicola is riding in the Auckland to Wellington express train. She notices that the surface of the water in the water cooler at the back of the carriage is not parallel with the floor. She thinks of several reasons for this. Here are her ideas.

  1. The train is going uphill.
  2. The train is moving at a constant speed.
  3. The train is travelling around a curve in the tracks.
  4. The train is accelerating at a constant rate.
a)
Which of Nicola's ideas could not be an explanation for what she saw?
 
_______
 
b) As the train left Taihape and picked up speed, she looked at the cooler from one side. The water surface was tilted as shown in the diagram. Which of Nicola's ideas would most likely explain this? _______

c)
If the water surface was tilted towards one side of the carriage, which of her ideas would best explain what she saw? _______
 
d) Draw what the water in the cooler would look like if the train braked suddenly.
 
Level:
5
Curriculum info: 
Science, Knowledge, Physical World
Keywords: 
physics concepts, forces, motion
Description of task: 
Task: Answer questions about the surface of water in a water cooler on a moving train. Assessment focus: forces.
Curriculum Links: 
Science capabilities
The capabilities focus is brought about by the conversations you have and the questions you ask
 
Capability: Interpret representations
This resource provides opportunities to discuss using evidence (diagrams and text) to make inferences.
Science capabilities: 
Interpret representations
Answers/responses: 
   

Y10 (06/1998)
a) 2 moderate
b) 4 easy
c) 3 very easy
d)
Any diagram which shows the water surface would slope from low at the back to high at the front of the cooler
or The water would "pile up" at the front of the cooler.
or A correctly drawn diagram similar to Question b) but with water slope reversed.
 very easy