Simple Machines
A tool or device made of one basic machine.
Simple machine
A system in which simple machines all work together; may contain subsystems and linkages.
complex machine
This is the measure of how much a machine multiplies the force applied to it.
mechanical advantage
Work happens when this occurs.
when a force is applied over distance
This is the mechanical advantage of single fixed pulley
1
These are 6 simple machines.
inclined plane, lever, pulley, wedge, wheel and axle, and screw
A student pushes a box with a force of 60 N for 5 m, but friction pushes back with a force of 20 N. How much work is done by the student's force?
300 joules
(60 N × 5 m = 300 J. The question asks for the work done by the student's force, not the net work.)"
This is the measure of how the speed of the object (and distance that it moves) is affected by a machine.
speed ratio
This is the work put into the machine when 800N is applied over 2m.
work input of 1600J
This is the Mechanical Advantage of a ramp that has an output arm of 1m and an input arm of 3m
3
A worker uses a pulley system with an ideal mechanical advantage of 5 to lift a 500 N load. Ignoring friction, how much force must the worker apply?
100 N
(500 N ÷ 5 = 100 N)
A wheel and axle has a wheel with a radius of 30 cm and an axle with a radius of 10 cm. What is the ideal mechanical advantage (IMA) of this wheel and axle?
IMA=3
(30 / 10 = 3)
This would be the mechanical advantage if the input force is 50N and the output force is 1000N.
mechanical advantage of 20
This is the measure of the amount of force applied to a given area.
pressure
If the input piston on a hydraulic system has a pressure of 100 Pa, the output piston will have this pressure.
100 Pa
Simple machines decrease this while increasing the other.
force and distance
A bicycle has a front gear with 48 teeth and a rear gear with 16 teeth. If the pedals make one complete rotation, how many times will the rear wheel rotate?
3 rotations (48 ÷ 16 = 3)
This would be the speed ratio if the input distance of a machine is 20m, and the output distance is only 5m.
speed ratio of 4
A hydraulic press has the same force applied, but the contact area is doubled. What happens to the pressure?
The pressure is cut in half. Increasing the area while keeping the force the same decreases pressure.
This is a system that uses liquids under pressure to move loads.
Hydraulics
Class 1: seesaw, scissors
Class 2: pliers, wheelbarrow, nutcracker, bottle opener, stapler
Class 3: human arm, tongs, hockey stick
This gear, when connected to a smaller driven gear, does this to the speed of the system.
Driver Gear
This converts useful energy into unusable energy, and therefore reduces the efficiency of machines.
friction
What is one advantage and one disadvantage of a hydraulic and a pneumatic system?
Advantage: Hydraulics can produce very large amounts of force
Disadvantage: Hydraulic systems can leak fluid
Advantage: Pneumatic systems are clean and safe because they use compressed air instead of liquids
Disadvantage: Pneumatic systems cannot produce as much force as hydraulic systems
If the input piston has a force of 10N and an area of 1m2, the output piston will have an area of this if the output force is 100N.
10m2