Calculate the moment of a 20 N force turning about an axis 2 m away.
2.
Calculate the sum of moments acting on the metre stick in Fig. 6.13.
50 cm 0 cm 3 N FIG. 6.13 3.
If the metre stick in Fig. 6.14 is in equilibrium, calculate the missing weight.
45 cm 0 cm 3 N FIG. 6.14 4.
If the metre stick in Fig. 6.15 is in equilibrium, calculate the missing distance from weight to fulcrum.
50 cm x 60 cm 20 N FIG. 6.15 5.
Calculate the moment about each of the points a–d in Fig. 6.16.
42 N a 0 cm 20 N 1 N FIG. 6.16 LEAVING CERTIFICATE PHYSICS 61
50 cm cd 65 cm
b 6 N 15 N 100 cm 15 N 95 cm 5 N H10. 9. 30 cm ? 55 cm 10 N 100 cm FIG. 6.17 5 N 8.
A tap has a diameter of 20 cm from end to end. If a person applies 10 N on each side, what torque is applied?
A cross-shaped wheel brace is used to tighten nuts on a car wheel. If the nuts require a torque of 100 N m and the wheel brace has a diameter of 25 cm from end to end, what force must be applied to tighten the nuts? If a single wrench only is available and the same force is applied, what length must the wrench be to achieve the same moment?
Two men hold a beam weighing 500 N of length 1 m. If man 1 holds one end and man 2 is to support three times as much weight as man 1, where should man 2 hold it?
B 200 mm 30 cm 12 N 60 cm 15 N 100 cm 4 N 7.
6.
Two children are playing on a seesaw of length 4 m. One child of 200 N sits 2 m from the pivot point. Where should the other child of 600 N sit to balance the seesaw?
A bolt can be tightened with an Allen key (Fig. 6.17). Calculate the moment on the bolt when:
(i) end A is inserted and a force of 20 N is applied
(ii) end B is inserted and a force of 20 N is applied.
