Turning Effect of Forces Answers [PDF]

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Name_______________________ IGCSE Physics Practical Activity



Turning Effect of forces The turning effect of a force is called the moment of a force. It depends on the size of the force and the distance between the force and the pivot.



The moment is large when the force is large or the distance is large. Moment (Nm) = Force (N) X Perpendicular Distance from Pivot (m



Example 1



Moment on the left = F x d = 50000 x 5 =250000Nm Moment on the right = F x d = 10000 25 =250000Nm Moments are the same so the crane is balanced.



Moments Practical Instructions 1. Place 1 mass piece at 7. Using the moment equation find the distance where a single mass piece must be placed in order to balance the system. Prove this practically.



2. Place 1 mass piece at 7. Using the moment equation find the distance where another 2 mass pieces must be placed in order to balance the system. Prove this practically.



3. Place 1 mass piece at 7. Using the moment equation find the distance where another 3 mass pieces must be placed in order to balance the system. Prove this practically.



4. Place 3 mass pieces at 7. Using the moment equation find the distance where another 4 mass pieces must be placed in order to balance the system. Prove this practically.



5. Place 3 mass pieces at 7. Using the moment equation find the distance where another 5 mass pieces must be placed in order to balance the system. Prove this practically.



6. Place 3 mass pieces at 7. Using the moment equation find the distance where another 7 mass pieces must be placed in order to balance the system. Prove this practically. 7. Place 3 mass pieces at 7. Using the moment equation find the distance where another 7 mass pieces must be placed in order to balance the system. Prove this practically.



Question 1 1.1.



ans



1.2.



1.3.



ans



unstable



ans



Question 2



Direction changes in circular motion, therefore velocity would change



For a changing velocity, acceleration is required. A force is needed for an object to accelerate



Towards the centre



The frictional force of the tyres and the road



ans



A, because it is at a further distance from the hinge/pivot



ans



4.



Moment = F x d = 3N x 40 cm = 120 N.cm



Moment = F x d = 2N x 30cm = 60 n.cm



Moments in clockwise = moments in anticlockwise 120 N.cm = 60 N.cm + Fx20cm……… 20F= 120 – 60….F =60/20 =3N



Moments in clockwise = moments in anticlockwise 1.2N x 20



= 2N x d ……………. 2d = 24…………d = 24/2 =12cm