Simple Machines
Instructions: From levers and pulleys to wheels and inclined planes, discover the six clever machines behind the everyday tools we all use.
- 1.
A seesaw on a playground is a classic example of which simple machine?
APulleyBLeverCWedgeDScrew - 2.
How many classic simple machines are recognized in science?
AFourBFiveCSixDEight - 3.
A ramp leading up to a loading dock is an example of which simple machine?
AWedgeBLeverCInclined planeDPulley - 4.
Which simple machine is used when you raise a flag up a flagpole?
ALeverBWedgeCPulleyDScrew - 5.
An axe splitting firewood uses which simple machine?
AScrewBWedgeCWheel and axleDLever - 6.
What is the fixed point on which a lever rests and rotates called?
APivot boltBFulcrumCAxleDBearing - 7.
A bolt that holds pieces of wood together uses which simple machine?
AInclined planeBWedgeCPulleyDScrew - 8.
A doorknob turning to open a door is an example of which simple machine?
ALeverBPulleyCWheel and axleDInclined plane - 9.
Using a movable pulley instead of a fixed pulley has what advantage?
AIt doubles the distance you must pull the ropeBIt cuts the effort force needed roughly in halfCIt makes the load move fasterDIt changes nothing — both pulleys do the same work - 10.
Which class of lever has the load between the fulcrum and the effort?
AFirst-class leverBSecond-class leverCThird-class leverDFourth-class lever - 11.
A spiral staircase is most closely related to which simple machine?
ALeverBPulleyCScrewDWedge - 12.
What term describes how many times a simple machine multiplies your input force?
APower ratioBMechanical advantageCForce coefficientDEffort index - 13.
Which simple machine does a zipper use when it closes?
ALeverBPulleyCWheel and axleDWedge - 14.
The ancient Egyptians are believed to have used inclined planes to build the pyramids. Roughly how much less force is needed to push a stone up a ramp that is 10 metres long and rises 1 metre compared to lifting it straight up?
AAbout 2 times less forceBAbout 5 times less forceCAbout 10 times less forceDAbout 20 times less force - 15.
No simple machine can increase both force and distance at the same time. This is a consequence of which scientific law?
ANewton's Third Law of MotionBThe Law of Conservation of EnergyCBoyle's LawDThe Law of Universal Gravitation
Answer Key
A seesaw is a lever — a rigid bar that pivots on a fixed point called a fulcrum. Levers help us lift or move objects with less effort.
There are six classic simple machines: the lever, wheel and axle, pulley, inclined plane, wedge, and screw. Together they form the building blocks of all mechanical devices.
An inclined plane is a flat surface set at an angle, like a ramp. It lets you move a heavy load to a higher level by spreading the effort over a longer distance.
A pulley is a wheel with a groove that guides a rope or cable, changing the direction of force. The flagpole uses a fixed pulley so you pull down on the rope to send the flag up.
An axe head is a wedge — two inclined planes joined back-to-back. As it is driven downward, the wedge shape pushes the wood apart sideways, multiplying the splitting force.
The fulcrum is the support point of a lever. Moving the fulcrum closer to the load lets you lift heavier objects with less effort — the principle Archimedes famously described.
A screw is essentially an inclined plane wrapped in a spiral around a cylinder. Each full turn moves the screw forward just a small distance, converting rotational force into powerful clamping force.
A doorknob is a wheel and axle — a larger wheel (the knob) turns a smaller axle (the shaft). Turning the larger knob takes less force than turning the narrow shaft directly.
A movable pulley shares the load between two rope segments, so you only need to exert about half the force to lift the same weight. The trade-off is that you must pull the rope twice as far.
In a second-class lever the load sits between the fulcrum and the point where you apply effort. A wheelbarrow is a perfect everyday example — the wheel is the fulcrum, the load rides in the bin, and you lift the handles.
A spiral staircase winds upward just like the thread of a screw. Both are inclined planes wrapped around a central axis, allowing a gradual climb rather than a steep vertical jump.
Mechanical advantage (MA) measures how much a machine multiplies force. An MA of 3 means the machine exerts three times the force you put in, though you must move the input through a greater distance.
The zipper slider acts as a wedge. As you pull the tab, the tapered slider forces the two rows of teeth together, and the opposite side separates them — two wedge actions in one small device.
The mechanical advantage of an inclined plane equals its length divided by its height (10 ÷ 1 = 10). So pushing the stone up that gentle ramp requires only about one-tenth the force of a direct vertical lift.
The Law of Conservation of Energy states that energy cannot be created or destroyed. A simple machine cannot produce more work than you put in, so gaining force always means sacrificing distance — and vice versa.