Chapter 4 Practice Paper: Turning Effects of Forces — question paper

Section A: Multiple-choice questions[10 marks]

Choose the one correct answer for each question.

1. 1

   The moment of a force measures

   1. Ahow large the force is
   2. Bhow fast the force is applied
   3. Cthe turning effect of the force about a pivot
   4. Dthe energy the force transfers
   ( )
2. 2

   A force of 20 N acts on a lever at a perpendicular distance of 0.35 m from the pivot. The moment of the force is

   1. A0.018 N m
   2. B7.0 N m
   3. C57 N m
   4. D70 N m
   ( )
3. 3

   Two children sit on a see-saw in equilibrium. The lighter child must sit

   1. Afurther from the pivot than the heavier child
   2. Bcloser to the pivot than the heavier child
   3. Cat the same distance as the heavier child
   4. Danywhere, since they balance
   ( )
4. 4

   A uniform metre ruler is pivoted at its 50 cm mark. The ruler balances. Where does its weight act?

   1. Aat the 0 cm mark
   2. Bat the 25 cm mark
   3. Cat the 100 cm mark
   4. Dat the 50 cm mark
   ( )
5. 5

   Loading a ship’s hold with heavy cargo low down makes the ship more stable because

   1. Athe total weight is reduced
   2. Bthe centre of gravity is lowered
   3. Cthe base becomes wider
   4. Dthe upthrust increases its moment
   ( )

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided.

1. 1

   A uniform metre ruler of weight 1.2 N is pivoted at its centre. A 2.0 N weight hangs from the 20 cm mark. A student hangs a single unknown weight on the ruler and it balances with the unknown weight at the 80 cm mark.

   1. (a)

      State the distance of the 2.0 N weight from the pivot.

      distance =m[1]
   2. (b)

      Calculate the moment of the 2.0 N weight about the pivot.

      moment =N m[2]
   3. (c)

      Calculate the unknown weight.

      weight =N[2]
   4. (d)

      Explain why the ruler’s own weight does not enter the calculation.

      [1]
2. 2

   A wheelbarrow carries a load of 240 N. The wheel acts as a pivot 0.45 m from the load’s line of action, and the gardener lifts at the handles 1.35 m from the pivot.

   1. (a)

      Calculate the moment of the load about the wheel axle.

      moment =N m[2]
   2. (b)

      Calculate the upward force the gardener must apply at the handles to lift the load.

      force =N[3]
   3. (c)

      State one advantage of moving the load closer to the wheel, with a reason.

      [2]
3. 3

   A non-uniform tree branch hangs from a pivot. A gardener suspends the branch from a string at two different points in turn; each time the branch settles in a particular orientation and a plumb line drawn from the pivot is marked.

   1. (a)

      Name the point of the branch found by this method.

      [1]
   2. (b)

      Explain why the branch always settles with its centre of gravity directly below the pivot.

      [3]
   3. (c)

      State why two suspension points are used rather than one.

      [1]
   4. (d)

      The branch is then cut short at the thin end. State and explain what happens to the position of its centre of gravity.

      [2]