from the fulcrum than the load. This means that the load will not move as far as the effort, but the force with which it moves is greater than the effort. The principle being applied is the same as in a first-class lever, which is that effort multiplied by distance is equal to the force multiplied by distance. If the distance between the effort and the fulcrum is increased and the distance of the load is closer to it, then the load that can be lifted is greater.


Figure 6 A good example is a person lifting a wheelbarrow with a heavy load. A small effort by the person enables them to lift a heavy load. The wheel of the wheelbarrow is the fulcrum.


Figure 7 Another example is a bottle opener. The effort is applied to the handle. The fulcrum is the point where the bar presses onto the bottle top and the load is the resistance, which has to be overcome in order to remove the top.


Figure 8 Nutcrackers are a good example of a compound second-class lever system. Two second-class levers work together in order to apply a force on a nut to crack the shell.


Figure 9 A luggage trolley is an example of a second-class lever. When it is being pushed, the load is between the fulcrum and the handles where the effort is applied. Although some of the load is in front of the fulcrum point (as in a first-class lever), the major part of the load is still between the fulcrum and the effort point.


Activity 3 Draw and sketch levers


1 Draw line drawings for the second-class levers in Figures 6–9 above. 2 Draw a sketch of the nutcracker and show where the effort is applied. You can use pencil crayons to add colour and shading to your drawing.


Unit 1 Revise levers and gears 103


TERM 3


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