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Moments couples levers

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PowerPoint to teach moments, couples & levers

PowerPoint to teach moments, couples & levers

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• 1. Moments, Levers &amp; Couples K WARNE
• 2. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE &gt;&gt; www.warnescience.net Moments and levers &#xF06C; Definition &#xF06C; Principle of moments &#xF06C; Couples &#xF06C; Calculations &#xF06C; Classes &#xF06C; Mechanical advantage
• 3. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE &gt;&gt; www.warnescience.net Moment of Force &#xF06C; The moment of a force about a point is the PRODUCT of the magnitude of the force and the perpendicular distance from the point to the line of the force. MOMENT = FORCE X DISTANCE = 5 x 0.25 = 1.25 N.m 5 N25 cm
• 4. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE &gt;&gt; www.warnescience.net Calculate the moment of the force, or &#x2026;&#x2026;&#x2026;.., due to each force when several forces act on the same object using the equation: &#xF074; = F&#xF05E; &#x2026; r F&#xF05E; Calculating Torque F1 F2&#xF05E; &#xF074; = F&#xF05E; x r = (F1x &#x2026;1) + (F2&#xF05E;x &#x2026;2) When calculating torque the &#x2026;&#x2026;&#x2026;&#x2026;.of all the PERPENDICULAR FORCES must be used. TORQUE
• 5. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE &gt;&gt; www.warnescience.net Equilibrium &#xF06C; For an object to be in equilibrium BOTH the sum of the &#x2026;&#x2026;&#x2026;&#x2026;&#x2026;.. acting on the object and the sum of the &#x2026;&#x2026;&#x2026;&#x2026;&#x2026;.of the forces must be ZERO. &#xF06C; Solve problems involving objects in equilibrium. F2 F3F1 FORCES (Linear) in equilibrium .: F1 + F2 + F 3 = &#x2026;&#x2026; MOMENTS in equilibrium .: &#x2026;&#x2026;&#x2026;&#x2026;&#x2026;. a fulcrum. (F1) (F1&#x2026;.) + (F2&#x2026;..) + (F3&#x2026;&#x2026;) = 0 x1 x2 If a 60 Kg person stands 2 meters from one end of a 3 meter scaffolding plank what force is needed to support each end of the plank?
• 6. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE &gt;&gt; www.warnescience.net Equilibrium Question F2 (F1. x1) + (F2. x2) + (F3.0) = 0 (F1.1)+((60x10)x2) + (F3x0) = 0 F1 + (1200) + 0 = 0 F1 = -1200 N .: F1 = 1200 N anticlockwise! A 1200 N force is needed at F1 to balance the plank! x1 x2 If a 60 Kg person stands on one end of a 3 meter scaffolding plank what force is needed to support him on the other end of the plank if the plank is balancing on a fulcrum 2m away from the 60kg person? ?? 60kg 2m F3 1 m F1 ?? Sum of all moments = zero Choose clockwise as POSITIVE! F3 = fulcrum
• 7. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE &gt;&gt; www.warnescience.net Levers &#x2022; Describe the terms &#x201C;load&#x201D; and &#x201C;effort&#x201D; for a lever &#x2022; Define &#x201C;mechanical advantage&#x201D; as the ratio of &#x201C;load/effort&#x201D; and calculate the mechanical advantage for simple levers &#x2026;&#x2026;&#x2026;&#x2026;.................. &#x2026;&#x2026; ...... .. If in equilibrium: &#x2026;&#x2026; x &#x2026;.. = &#x2026;&#x2026; x &#x2026;..
• 8. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE &gt;&gt; www.warnescience.net Levers &#x2022; Describe the terms &#x201C;load&#x201D; and &#x201C;effort&#x201D; for a lever &#x2022; Define &#x201C;mechanical advantage&#x201D; as the ratio of &#x201C;load/effort&#x201D; and calculate the mechanical advantage for simple levers LoadEffort e l If in equilibrium: E x e = L x l Mechanical Advantage Load Force Effort Force F E OR = e l == Effort distance Load distance =
• 9. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE &gt;&gt; www.warnescience.net Mechanical Advantage &#xF06C; Mechanical Advantage is the RATIO of the LOAD to the EFFORT. Apply the concept of mechanical advantage to everyday situations. Mechanical Advantage Load Force Effort Force N Load L Effort E l e F E OR = e l == Effort distance Load distance =
• 10. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE &gt;&gt; www.warnescience.net Types of Levers Class 1Effort Load Class 2 Effort Load Class 3 Effort Load Load Load Effort Effort o.75 o.25 o.75 o.75 o.25 o.25 Type 1 F in middle MA = e/l= 0.75/0.25 = 3 Type 2 F at end L in middle M.A. = e/l = 1/0.25 = 4 Type 3 F in mid L at end M.A. = e/l = 0.25/0.75 = 0.3 The weight of the lever helps in type 1 but not T2!
• 11. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE &gt;&gt; www.warnescience.net Examples of Levers
• 12. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE &gt;&gt; www.warnescience.net Force Couple A special case of moments is a couple. A couple consists of two parallel forces that are equal in magnitude, opposite in direction and do not act in a straight line but are separated by a distance (d). It does not produce any translation, only rotation. The resultant force of a couple is zero. BUT, the resultant of a couple is not zero; it is a pure moment. Example: A steering wheel of diameter 0.75 m is turned by a force of 20 N applied to each end. Calculate the magnitude of the force couple: Couple = F x d = (20 x 0.75) = 15 N.m F F d d 2 d 2 Couple = Total Turning Moment = (F x d/2) + (F x d/2) = &#xBD; (F x d) + &#xBD; (F x d) = F x d
• 13. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE &gt;&gt; www.warnescience.net Hi - This is a SAMPLE presentation only. My FULL presentations, which contain loads more slides (with all the gaps filled in) as well as other resources, are freely available on my resource sharing website: www.warnescience.net (paste into your browser if link above does not work) Have a look and enjoy! Keith Warne