[Music] think of a spanner loosening a fixed nut or a child on a seesaw or a door opening around a fixed hinge all of these things are connected by something called moments a moment is the turning force around a fixed pivot the pivot is the nut or the middle of the seesaw or the hinge we can have one moment acting which results in a turning force or if something is balanced or in equilibrium the moments are equal and opposite to be balanced this lighter child needs to sit further away from the pivot and the heavier child needs to be closer this is because the size of a moment is determined by the force and a distance so the moment of the lighter person is 500 newtons multiplied by two meters 1000 newton meters and the heavier person is a thousand times one meter to also give one thousand newton meters they're perfectly balanced on their seesaw did you notice that moments are measured in newton meters n m because force is measured in newtons n and distance in meters note that the distance must be the perpendicular distance from the pivot to force here's another example can you work out what moments the woman is applying to tighten the wheel nut pause the video and work it out did you get three newton meters were you careful to change the 30 centimeters into meters we can also place this formula into a formula triangle force equals moments divided by distance distance equals moments divided by force and moments as we already know is force times distance here are two more questions for you to try pause the video and work them out did you get both questions right for this seesaw we do actually say clockwise moments and anti-clockwise moments and for something to be balanced the clockwise and anti-clockwise moments must be equal so there we have moments they're measured in newton-meters and are the force multiplied by the perpendicular distance