// Numbas version: finer_feedback_settings
{"name": "Harry's copy of Find curl and divergence of a vector field", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"parts": [{"prompt": "<p>$\\boldsymbol{\\nabla}\\times\\boldsymbol{u}=($[[0]]$,$[[1]]$,$[[2]]$)$.</p>", "scripts": {}, "type": "gapfill", "marks": 0, "gaps": [{"showpreview": true, "checkingaccuracy": 0.001, "scripts": {}, "vsetrangepoints": 5, "answersimplification": "all", "vsetrange": [0, 1], "checkvariablenames": true, "showCorrectAnswer": true, "checkingtype": "absdiff", "answer": "{f1*p9}*x^{p8}*y^{p9-1}+{-d1*p6}*x^{p5}*z^{p6-1}", "type": "jme", "marks": 1, "expectedvariablenames": ["x", "y", "z"]}, {"showpreview": true, "checkingaccuracy": 0.001, "scripts": {}, "vsetrangepoints": 5, "answersimplification": "all", "vsetrange": [0, 1], "checkvariablenames": true, "showCorrectAnswer": true, "checkingtype": "absdiff", "answer": "{b1*p3}*y^{p2}*z^{p3 -1}+{-f1*p8}*x^{p8-1}*y^{p9}", "type": "jme", "marks": 1, "expectedvariablenames": ["x", "y", "z"]}, {"showpreview": true, "checkingaccuracy": 0.001, "scripts": {}, "vsetrangepoints": 5, "answersimplification": "all", "vsetrange": [0, 1], "checkvariablenames": true, "showCorrectAnswer": true, "checkingtype": "absdiff", "answer": "{d1*p5}*x^{p5-1}*z^{p6}+{-b1*p2}*y^{p2-1}*z^{p3}", "type": "jme", "marks": 1, "expectedvariablenames": ["x", "y", "z"]}], "showCorrectAnswer": true}, {"prompt": "<p>$\\boldsymbol{\\nabla\\cdot u}=$ [[0]].</p>", "scripts": {}, "type": "gapfill", "marks": 0, "gaps": [{"showpreview": true, "checkingaccuracy": 0.001, "scripts": {}, "vsetrangepoints": 5, "answersimplification": "all", "vsetrange": [0, 1], "checkvariablenames": true, "showCorrectAnswer": true, "checkingtype": "absdiff", "answer": "{a1*p1}*x^{p1-1}+{c1*p4}*y^{p4-1}+{e1*p7}*z^{p7-1}", "type": "jme", "marks": 1, "expectedvariablenames": ["x", "y", "z"]}], "showCorrectAnswer": true}, {"prompt": "<p>Is the vector field $\\boldsymbol{u}$ irrotational?</p>", "scripts": {}, "shuffleChoices": false, "choices": ["<p>{irrotational}</p>", "<p>{notirrotational}</p>"], "matrix": [1, 0], "minMarks": 0, "showCorrectAnswer": true, "distractors": ["", ""], "maxMarks": 0, "type": "1_n_2", "displayType": "radiogroup", "marks": 0, "displayColumns": 0}, {"prompt": "<p>Is the vector field $\\boldsymbol{u}$ solenoidal?</p>", "scripts": {}, "shuffleChoices": false, "choices": ["<p>{solenoidal}</p>", "<p>{notsolenoidal}</p>"], "matrix": [1, 0], "minMarks": 0, "showCorrectAnswer": true, "distractors": ["", ""], "maxMarks": 0, "type": "1_n_2", "displayType": "radiogroup", "marks": 0, "displayColumns": 0}], "variables": {"notsolenoidal": {"definition": "if(n=2,\"No\",\"Yes\")", "group": "Ungrouped variables", "name": "notsolenoidal", "templateType": "anything", "description": ""}, "a1": {"definition": "if(n=2,0,random(1..9))", "group": "Ungrouped variables", "name": "a1", "templateType": "anything", "description": ""}, "p4": {"definition": "random(1..9)", "group": "Ungrouped variables", "name": "p4", "templateType": "anything", "description": ""}, "d1": {"definition": "if(n=1,0,random(1..9))", "group": "Ungrouped variables", "name": "d1", "templateType": "anything", "description": ""}, "c1": {"definition": "if(n=2,0,random(1..9))", "group": "Ungrouped variables", "name": "c1", "templateType": "anything", "description": ""}, "p1": {"definition": "random(1..9)", "group": "Ungrouped variables", "name": "p1", "templateType": "anything", "description": ""}, "p3": {"definition": "random(1..9)", "group": "Ungrouped variables", "name": "p3", "templateType": "anything", "description": ""}, "irrequal": {"definition": "if(n=1,\"is equal\",\"is not equal\")", "group": "Ungrouped variables", "name": "irrequal", "templateType": "anything", "description": ""}, "notirrotational": {"definition": "if(n=1,\"No\",\"Yes\")", "group": "Ungrouped variables", "name": "notirrotational", "templateType": "anything", "description": ""}, "p7": {"definition": "random(1..9)", "group": "Ungrouped variables", "name": "p7", "templateType": "anything", "description": ""}, "p2": {"definition": "random(1..9)", "group": "Ungrouped variables", "name": "p2", "templateType": "anything", "description": ""}, "p6": {"definition": "random(1..9)", "group": "Ungrouped variables", "name": "p6", "templateType": "anything", "description": ""}, "n": {"definition": "random(0..2)", "group": "Ungrouped variables", "name": "n", "templateType": "anything", "description": ""}, "solenoidal": {"definition": "if(n=2,\"Yes\",\"No\")", "group": "Ungrouped variables", "name": "solenoidal", "templateType": "anything", "description": ""}, "f1": {"definition": "if(n=1,0,random(1..9))", "group": "Ungrouped variables", "name": "f1", "templateType": "anything", "description": ""}, "isirr": {"definition": "if(n=1,\"is irrotational\",\"is not irrotational\")", "group": "Ungrouped variables", "name": "isirr", "templateType": "anything", "description": ""}, "p9": {"definition": "random(1..9 except p6)", "group": "Ungrouped variables", "name": "p9", "templateType": "anything", "description": ""}, "solequal": {"definition": "if(n=2,\"is equal\",\"is not equal\")", "group": "Ungrouped variables", "name": "solequal", "templateType": "anything", "description": ""}, "b1": {"definition": "if(n=1,0,random(1..9))", "group": "Ungrouped variables", "name": "b1", "templateType": "anything", "description": ""}, "e1": {"definition": "if(n=2,0,random(1..9))", "group": "Ungrouped variables", "name": "e1", "templateType": "anything", "description": ""}, "p5": {"definition": "random(1..9 except p2)", "group": "Ungrouped variables", "name": "p5", "templateType": "anything", "description": ""}, "p8": {"definition": "random(1..9 except p3)", "group": "Ungrouped variables", "name": "p8", "templateType": "anything", "description": ""}, "issol": {"definition": "if(n=2,\"is solenoidal\",\"is not solenoidal\")", "group": "Ungrouped variables", "name": "issol", "templateType": "anything", "description": ""}, "irrotational": {"definition": "if(n=1,\"Yes\",\"No\")", "group": "Ungrouped variables", "name": "irrotational", "templateType": "anything", "description": ""}}, "question_groups": [{"name": "", "pickQuestions": 0, "pickingStrategy": "all-ordered", "questions": []}], "preamble": {"css": "", "js": ""}, "showQuestionGroupNames": false, "advice": "<p>The curl of a vector field $\\boldsymbol{u}=\\pmatrix{u_x,u_y,u_z}$ is given by</p>\n<p>\\[\\boldsymbol{\\nabla}\\times\\boldsymbol{u}=\\pmatrix{\\frac{\\partial u_z}{\\partial y}-\\frac{\\partial u_y}{\\partial z},\\frac{\\partial u_x}{\\partial z}-\\frac{\\partial u_z}{\\partial x},\\frac{\\partial u_y}{\\partial x}-\\frac{\\partial u_x}{\\partial y}}.\\]</p>\n<p>The divergence of the same vector field is given by</p>\n<p>\\[\\boldsymbol{\\nabla\\cdot u}=\\frac{\\partial u_x}{\\partial x}+\\frac{\\partial u_y}{\\partial y}+\\frac{\\partial u_z}{\\partial z}.\\]</p>\n<h4>a)</h4>\n<p>By straightforward partial differentiation</p>\n<p>\\[\\boldsymbol{\\nabla\\cdot u}=\\pmatrix{\\simplify{{f1*p9}*x^{p8}*y^{p9-1}+{-d1*p6}*x^{p5}*z^{p6-1}},\\simplify{{b1*p3}*y^{p2}*z^{p3 -1}+{-f1*p8}*x^{p8-1}*y^{p9}},\\simplify{{d1*p5}*x^{p5-1}*z^{p6}+{-b1*p2}*y^{p2-1}*z^{p3}}}.\\]</p>\n<h4>b)</h4>\n<p>Again, by partial differentiation</p>\n<p>\\[\\boldsymbol{\\nabla\\cdot u}=\\simplify{{a1*p1}*x^{p1-1}+{c1*p4}*y^{p4-1}+{e1*p7}*z^{p7-1}}.\\]</p>\n<p>A vector field is irrotational if its curl is equal to the zero vector; a vector field is solenoidal if its divergence is equal to zero.</p>\n<h4>c)</h4>\n<p>Since $\\boldsymbol{\\nabla}\\times\\boldsymbol{u}$ {irrequal} to the zero vector, the vector field {isirr}.</p>\n<h4>d)</h4>\n<p>Since $\\boldsymbol{\\nabla\\cdot u}$ {solequal} to zero, the vector field {issol}.</p>", "functions": {}, "rulesets": {}, "ungrouped_variables": ["f1", "irrequal", "isirr", "b1", "d1", "issol", "e1", "irrotational", "a1", "c1", "solenoidal", "p2", "p3", "solequal", "p1", "p6", "p7", "p4", "p5", "notsolenoidal", "p8", "p9", "notirrotational", "n"], "tags": ["checked2015", "MAS2104"], "type": "question", "metadata": {"notes": "", "licence": "Creative Commons Attribution 4.0 International", "description": "<p>Curl and divergence of a vector field. &nbsp;Determine whether the vector field is irrotational or solenoidal.</p>"}, "variable_groups": [], "statement": "<p>For the vector field $\\boldsymbol{u}=\\pmatrix{\\simplify{{a1}*x^{p1}+{b1}*y^{p2}*z^{p3}},\\simplify{{c1}*y^{p4}+{d1}*x^{p5}*z^{p6}},\\simplify{{e1}*z^{p7}+{f1}*x^{p8}*y^{p9}}}$, calculate $\\boldsymbol{\\nabla}\\times\\boldsymbol{u}$ and $\\boldsymbol{\\nabla\\cdot u}$, and determine whether $\\boldsymbol{u}$ is irrotational or solenoidal, or both.</p>", "variablesTest": {"condition": "", "maxRuns": 100}, "name": "Harry's copy of Find curl and divergence of a vector field", "contributors": [{"name": "Harry Flynn", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/976/"}]}]}], "contributors": [{"name": "Harry Flynn", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/976/"}]}