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Turning Effect of Force. Shie Yu Hao (22) Per Sheng Xiang (19). Hinge. Pivot. Force B -A larger force is needed if applied further to hinge. S mall recap. 2 factors which the door turns depends: Magnitude (Amount) of force Distance of the force applied from the pivot. Force A
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Turning Effect of Force Shie Yu Hao (22) Per Sheng Xiang (19)
Hinge Pivot Force B -A larger force is needed if applied further to hinge Small recap • 2 factors which the door turns depends: • Magnitude (Amount) of force • Distance of the force applied from the pivot Force A -A smaller force is needed if applied nearer to hinge
Measure the turning effect • Now, you would learn how to calculate the force that has been exerted!
Definition: The moment of a force (torque) is the product of the force and the perpendicular distance from the pivot to the line of action of the force. Moment of Force= FxD where F is the force and D is the perpendicular distance from the pivot Moment of a force
Moment of Force can move anti-clockwise or clockwise. Hinge • Force A • -A smaller force is needed if applied nearer to hinge Force B -A larger force is needed if applied further to hinge
Perpendicular to pivot C- 10cm D- 30cm Weight Z= 5N A B Find the moment of force applied at A and B.
A Similarly, C- 10cm Perpendicular distance of C = 10cm= 0.1m Moment of Weight Z about the pivot(A) = Z x C = 5N (Weight) x C (Distance) =5x0.1 =o.5N m The force needed to lift the weight Z is 0.5N m. Weight Z= 5N
B C+D- 10cm+30cm=40cm Perpendicular distance of C+D = 40cm= 0.4m Moment of Weight Z about the pivot(A) = Z x C = 5N (Weight) x C+D (Distance) =5x0.4 =2.0N m The force needed to lift the weight Z is 2.0N m. Weight Z= 5N
d d Sg Mg Equilibrium How did the objects balance? The force acting on the two objects would be the same, right?
Remember, Moment of Force can move anti-clockwise or clockwise. So, d d Mg Sg Mg= Mass x gravitational force Sg= Total standard masses x gravitational force Anti-clockwise moment= Mg x d Clockwise moment= Sg x d Since they are equal: Mg x d= Sg x d M= S In simpler words, The above equation derived us why the beam is balanced.
What happens if the distance of your 2 objects are different away from the pivot? • Can we still calculate the force exerted? • OF COURSE! WE WOULD USE PRINCIPLE OF MOMENTS! Principle of Moments
From the above equation: Mg x d= Sg x d We know that the clockwise moment of force is the same as the anti-clockwise moment of force in an equilibrium Let’s do an experiment to prove it! Principle of Moments
d1 d2 W1- 0.5N W2- 0.4N We would change the distance of d1 and d2 for every experiment we do. Observe the results later.
Optional • Ask the class to try out the experiment themselves!
From the above experiment, We know that anti-clockwise moments of force will be the same as clockwise moments of force when there are balanced. Now, how do we find the distance if we are given the moments of force and weight? Just reverse all the steps! Force/ Weight = Distance