And how they work
What's a Machine?
How this works is by decreasing the input force ( the force that you put into the machine) , and increasing the output force ( the force that the machine applies to do the task), in most cases.
Types Of Levers
In first class lever, they have the fulcrum in between the input force and the load, as shown in the figure below.
In second class levers, the load is between the fulcrum and the input force, as demonstrated in the diagram below.
Lastly, third class levers, the input force is between the fulcrum and the load, as shown below.
Force -Distance Trade Off
What the lever does is make work easier (in most cases). It does this by decreasing the force you apply to the lever, by increasing the distance at which the force is applied.
A fixed pulley is connected to something that doesn't move, hence the word fixed ( as in fixed position). To use a fixed pulley, you pull down the rope to lift the load. The direction of the force changes. Since the size of the output force is the same as the input force, the mechanical advantage (MA) is 1.
These types of pulleys are connected directly to the object that is being moved, which is the load. The direction does not change, but the size of the force does. The mechanical advantage (MA) of this pulley is 2. This means less force is needed to move a heavier load.
Block and Tackles
If you combine a fixed pulley and a movable pulley, you form a pulley system, know as a block and tackle. The mechanical advantage (MA) of this simple machine is equal to the number of sections of rope in the system.
Wheel and Axle
If the length of the inclined plane is much greater than the height, the mechanical advantage is large. This means that an inclined plane with a gradual slope needs less force to move objects than a steep sloped one.
A wedge has a greater mechanical advantage if it is long and thin. This means there is a smaller input force over a longer distance.
To find the mechanical advantage of A screw, you have to find the length and the width of the inclined plane that is wrapped around the cylinder. ( This is just calculating the
MA of an inclined plane). The longer the spiral on a screw and the closer the threads, the greater the screw's mechanical advantage.
Most compound machines have a very low mechanical efficiency ( measures the ratio of work output to work input in a machine).Because there are various parts moving in a compound machine, the efficiency is low due to the fact that more parts are moving and are making contact with each other. This means more friction, which lowers the output force.