![](\"resources/question-resources/Max_height_v2.jpg\"/)
Tree sap rises in the trees, in part, due to capillary action. However water also evaporates from the leaves creating a pressure differential along the capillary which also helps water move upwards.
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", "templateType": "randrange"}, "new_max_h": {"name": "new_max_h", "group": "Ungrouped variables", "definition": "(2*0.0728+(r*10^(-6))*101325)/(1000*(r*10^(-6))*9.8)", "description": "", "templateType": "anything"}}, "variablesTest": {"condition": "", "maxRuns": 100}, "ungrouped_variables": ["max_h", "r", "new_max_h"], "variable_groups": [], "functions": {}, "preamble": {"js": "", "css": ""}, "parts": [{"type": "information", "useCustomName": false, "customName": "", "marks": 0, "showCorrectAnswer": true, "showFeedbackIcon": true, "scripts": {}, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "adaptiveMarkingPenalty": 0, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "prompt": "Consider the following simple model for the rising of tree sap. Let us say that we have an open beaker with water. The atmosphere above the water has a pressure $P_{out}$. A capillary tube is inserted in the beaker. The pressure inside the capilary tube is $P_{in}$. Let us say that $P_{in}$ is smaller than $P_{out}$. The water will rise in the capillary due to the difference in pressures.
\n\n
What is the height the water rises due to this pressure difference (i.e. not taking into account capillary action)? Write the formula for $h$ with respect to $P_{out}$ (write this in numbas as P1), $P_{in}$ as (write this in numbas as P2), the density of water (write as d) and the gravitational accelaration (write as g).
Hint: You might want to consider equating the different forces at the thick dashed line inside the capilary.
$h$ = [[0]]
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\nNotice that this is the same as asking what is the maximum length of straw you can drink through.
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\nAgain, provide your answer to the nearest metre.
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