Simple mechanisms Flashcards
what is a mechanism
a mechanism consists of a set of moving parts that are used to make work easier so that we use less energy machines all contain mechanisms
E.g a bike - wheels, gears, axles …
meaning: lever, fulcrum, effort, load, moments, mechanical advantage, input and output
lever - a simple mechanism that consists of a bar that turns around a fixed point. it is used to move weights
fulcrum - the point of movement / pivot on which the arm of the lever moves
effort - a force exerted in a mechanism that enables it to work
load - the object / mass that has to moved, lifted or cut
moments - turning forces around a fulcrum
mechanical advantage - when machines / mechanisms enable us to move large loads with little effort
inputs - the amount of force applied to a lever
outputs - the force the lever produces to move a load
how do levers work
they all have a rigid, straight bar that turns around a fixed point, a fulcrum. they also contain a effort and a load
how can you change the amount of power you use of gain on a lever
if you change the position of the fulcrum you can gain extra power with less effort visa versa
describe a mechanical advantage
aka the MA and we call it this because it enables us to move a heavy load with less effort
how do we measure load and effort
newtons (N)
what is a first-class lever and give some examples
it is a lever in which the fulcrum is placed in between the load and the effort. when the applied force pushes on 1 end the other contain the load goes up in the opposite direction to the effort.
E.g a see-saw, a claw hammer, a scale and scissors
describe the MA in a first-class lever
it depends on the distance of the fulcrum in relation to the load and effort. we show mechanical advantage as MA > 1
but and item such as a scale we show it like this MA = 1
what is a second-class lever and give some examples
it is a lever in which the load is in between the fulcrum and the effort. they cause the load to move in the same direction as the effort, but the input moves further than the output.
E.g a wheelbarrow, a car bonnet, a nutcracker and a hole punch
describe the MA in a second-class lever
they always increase the effort force and give mechanical advantage, but like a first-class the force magnitude depends on the distance of the load from the fulcrum. if you want to move a heavier load with less effort you move the load closer to the fulcrum. the force on the load is increase, but the distance the load moves is not far when we do this it is MA > 1
what is a third-class lever and name some examples
it is a lever in which the effort is in between the load and the fulcrum, the force and the load move in the same direction. it doesn’t make it the job easier and there is no mechanical advantage so MA
meaning - linkage, paired or linked lever, complex linkage
linkage - 2 or more joined levers
paired / linked lever - two levers that are joined and work together
complex linkage - a number a levers joined together
where is the fulcrum usually on paired levers
where the 2 levers join
when are simple linked first-class levers use
in cutting, clamping and pinching
describe simple linked second-class levers
very powerful and used to crack nuts, clamp holes and press garlic …
