To start A meter rule pivoted at its

To start A meter rule, pivoted at its centre of mass, supports a 3. 0 N weight at its 5. 0 cm mark, a 2. 0 N weight at its 25 cm mark and a weight W at its 80 cm mark. a) Sketch a diagram of the situation b) calculate the weight W

A LEVEL PHYSICS Year 1 Advanced Moments A* A B C • I can calculate the support force when a single support is in operation (Grade d) • I can calculate force on either support when two supports are in place (Grade b) • I can describe what is meant by a couple (Grade c)

Moment = Force x Perpendicular Distance Determine the units for momentum

Support force is equal to the weight of the object (i. e. ruler) plus the weight of any object place upon it. S = W 1 + W 2 + Wo It is the reaction force of the object on the pivot.

A 30 cm ruler of 10 N is balanced on a knife edge with a 0. 5 kg mass on the 5 cm mark and a 0. 75 kg mass on the 27 cm mark. a) Draw a diagram b) Calculate the support (reaction) force

Sy Sx dx x dy W y D When there is more than one support involved to calculate the reaction force at each support you need to take moments about the other support:

A uniform ladder of weight 400 N and length 3. 5 m is held horizontally by two people. One person supports the ladder at end A and the other supports it at point B, a distance of 1. 0 m from C (the opposite end to A). a) Draw the set up and the three forces b) Calculate the supporting force provided by the person at i) A ii) B c) The person at A releases the ladder. Calculate the moment which the person at B must provide to keep the ladder horizontal

Answers B A 400 N • B i)120 N ii) 280 N • C) 300 Nm (400 x 0. 75) C

Couples A pair of forces of equal size which act parallel to each other, but in opposite directions. This doesn’t cause a resultant linear force but does produce a turning effect. Try finding a general formula for the overall moment of the following turning forces.

A cyclist turns a sharp corner by applying equal but opposite forces of 25 N to the ends of the handlebars. The length of the handlebars is 0. 60 m. Calculate the moment applied to the handlebars.

Exam questions worksheet

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