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Moments couples levers
Moments couples levers
Moments couples levers
Moments couples levers
Moments couples levers
Moments couples levers
Moments couples levers
Moments couples levers
Moments couples levers
Moments couples levers
Moments couples levers
Moments couples levers
Moments couples levers
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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 & Couples K WARNE
  • 2. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Moments and levers  Definition  Principle of moments  Couples  Calculations  Classes  Mechanical advantage
  • 3. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Moment of Force  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 >> www.warnescience.net Calculate the moment of the force, or ……….., due to each force when several forces act on the same object using the equation:  = F … r F Calculating Torque F1 F2  = F x r = (F1x …1) + (F2x …2) When calculating torque the ………….of all the PERPENDICULAR FORCES must be used. TORQUE
  • 5. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Equilibrium  For an object to be in equilibrium BOTH the sum of the …………….. acting on the object and the sum of the …………….of the forces must be ZERO.  Solve problems involving objects in equilibrium. F2 F3F1 FORCES (Linear) in equilibrium .: F1 + F2 + F 3 = …… MOMENTS in equilibrium .: ……………. a fulcrum. (F1) (F1….) + (F2…..) + (F3……) = 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 >> 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 >> www.warnescience.net Levers • Describe the terms “load” and “effort” for a lever • Define “mechanical advantage” as the ratio of “load/effort” and calculate the mechanical advantage for simple levers ………….................. …… ...... .. If in equilibrium: …… x ….. = …… x …..
  • 8. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> www.warnescience.net Levers • Describe the terms “load” and “effort” for a lever • Define “mechanical advantage” as the ratio of “load/effort” 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 >> www.warnescience.net Mechanical Advantage  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 >> 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 >> www.warnescience.net Examples of Levers
  • 12. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> 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) = ½ (F x d) + ½ (F x d) = F x d
  • 13. SAMPLE ONLY SAMPLE ONLY SAMPLE ONLY For FULL presentation click HERE >> 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

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