e":"3.6.4 Weight acting through a point (A-level only) Flashcards","topicId":"feb4e3a0-2985-48a6-9df6-1a332704545e","topicSlug":"weight-acting-through-a-point","cards":[{"id":"9f7828e6-f80f-45fc-a6a6-f4d213831aa9","cardType":"basic","front":"How is a rigid body's distributed weight modelled when calculating moments?","back":"As one downward force acting through its centre of mass.","points":1,"mcqOptions":null},{"id":"44fff792-f853-43f1-82fa-63781fa087f3","cardType":"cloze","front":"The magnitude of a body's weight is $\\text{[...]}$.","back":"The magnitude of a body's weight is $\\boxed{W=mg}$.","points":null,"mcqOptions":null},{"id":"c0a99f36-28bb-490e-babf-39114a1435c6","cardType":"basic","front":"What value of $g$ should be used unless stated otherwise?","back":"$9.8\\text{ m s}^{-2}$","points":1,"mcqOptions":null},{"id":"d58dc6c9-f53e-4fe2-b052-d73f6c5fd95c","cardType":"basic","front":"Where does the weight of a uniform rod act?","back":"Vertically downwards through its midpoint.","points":1,"mcqOptions":null},{"id":"cb1cd937-12df-4e17-aa5d-720b46cd9412","cardType":"basic","front":"Where is the centre of mass of a uniform rectangular lamina?","back":"At the intersection of its diagonals.","points":1,"mcqOptions":null},{"id":"f28c258f-67c2-4421-824d-0e88786f9c3b","cardType":"basic","front":"Where is the centre of mass of a uniform circular disc?","back":"At its centre.","points":1,"mcqOptions":null},{"id":"06112588-d474-44a9-bc9b-2eda128f04a8","cardType":"basic","front":"Why can a non-uniform body's centre of mass differ from its geometrical centre?","back":"Its mass is not evenly distributed.","points":2,"mcqOptions":null},{"id":"1cc3204e-126a-41ec-8ecc-51d5608963f0","cardType":"cloze","front":"The magnitude of a moment is $\\text{[...]}$, where $d$ is the perpendicular distance to the force's line of action.","back":"The magnitude of a moment is $\\boxed{M=Fd}$, where $d$ is the perpendicular distance to the force's line of action.","points":null,"mcqOptions":null},{"id":"4d7fb37e-0791-45b3-b35d-0e351bb86dc9","cardType":"basic","front":"What distance is used when calculating a force's moment about a point?","back":"The perpendicular distance to the force's line of action.","points":1,"mcqOptions":null},{"id":"25fba202-bd13-48f9-ae2d-5dbb46c1c67a","cardType":"cloze","front":"Because weight acts vertically, its line of action is the [ ].","back":"Because weight acts vertically, its line of action is the vertical line through the centre of mass.","points":null,"mcqOptions":null},{"id":"3391ec82-c387-41c6-a1dc-e424fce18fa5","cardType":"basic","front":"What additional information must accompany the magnitude of a moment?","back":"Whether it is clockwise or anticlockwise.","points":1,"mcqOptions":null},{"id":"2fed1dd6-6ab0-4668-a1ac-8f941dbb560f","cardType":"basic","front":"A force acts through a chosen moment centre. What is its moment about that point?","back":"Zero, because its perpendicular distance is zero.","points":2,"mcqOptions":null},{"id":"01e1386e-2048-41b4-8fb9-524d167f6dc8","cardType":"basic","front":"When does a body's weight have zero moment about a pivot?","back":"When the pivot lies vertically above or below the centre of mass.","points":1,"mcqOptions":null},{"id":"4dec4fd1-36b5-43f9-a69d-4b483b2ed412","cardType":"cloze","front":"For a uniform rod of length $L$ inclined at angle $\\theta$ to the horizontal, the perpendicular distance for its weight is $\\text{[...]}$.","back":"For a uniform rod of length $L$ inclined at angle $\\theta$ to the horizontal, the perpendicular distance for its weight is $\\boxed{\\frac{L}{2}\\cos\\theta}$.","points":null,"mcqOptions":null},{"id":"7fea144c-5471-42f4-95