P3- using physics to make things work

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moments

• turning effect of a force is a moment
• moment= force x perpendicular distance from the line of action of the force to the pivot
• increasing the moment- force must increase, distance to pivot must increase
• force we are trying to move is the load and increasing distance acts as a force multiplier and makes the effort to move the load less

centre of mass

• centre of mass is were the mass is concentrated into one point
• any object suspended will come to rest at its centre of mass directly below point of suspension- object will then be at equilibirum
• finding centre of mass- cut a shape of card, punch a hole in three places, suspend the card from a stand with a plumbline hung infront, wait for card to come to rest and draw line where plumbline hangs, do the same for the two other holes and the centre of mass is where the three lines meet
• depends on the shape of the object sometimes its outside the object
• for a symmetrical object the centre of mass is at the centre of this

moments in balance

• if an object is at equilibrium it is balanced and not turning
• total clockwise and anticlockwise distance of a moment around a point are equal when object is at equilibrium
• eg of a principle moment= seasaw or balance scales

stability

• line of…