Cov tsheb kauj vab ua haujlwm li cas?
Millions of people around the world use bicycles. People ride their bikes to exercise, commute, deliver packages, compete in races or just ride for fun. Cycling may seem easy to some, but it's actually quite complicated. Both the rider and the bike play an integral role in the process, which is actually more of a science than an art. How does this two-wheeled object drive?
Kev sib xyaw ntawm lub tsheb kauj vab
Tsheb kauj vab ncej, kov system (nrog rau pem hauv ntej diav rawg, tuav), tsheb kauj vab ncej, pem hauv ntej thiab nram qab log, saw system, brakes, av nkos, tswb thiab lwm yam accessories, cov kis las tsheb kauj vab kuj muaj pem hauv ntej thiab nram qab hloov systems.
Lub tsheb kauj vab nres ua haujlwm li cas
Txawm hais tias koj pedal ceev npaum li cas, koj yuav tsum nres. Nres ntawm tsheb kauj vab ua haujlwm siv kev sib txhuam. Txawm hais tias qee lub tsheb kauj vab tam sim no tau nruab nrog disc nres, ntau tus tseem siv cov tsoos caliper -style rim brakes nrog khau.
Yuav ua li casbicyclehandlebarswork
Lub handlebars ntawm lub tsheb kauj vab yog ib hom lever. Ntev ntev handlebars muab leverage, uas ua rau nws yooj yim dua rau pivot lub log pem hauv ntej ntawm lub tsheb kauj vab. Qhov sib nrug ntxiv rau koj qhov chaw koj txhais caj npab, ntau qhov cua tiv thaiv koj tsim. Cov txheej txheem sab nrauv ntawm cov handlebars yog rau kev tswj, thiab cov khoom sab hauv yog rau gliding.
Yuav ua li castsheb tuamncej ua haujlwm
Admittedly, if a person weighing 140–170 pounds uses the bike, the bike must not be damaged. This means that the frame of the bike has to be very stiff. With traditional bikes, the frame is made of strong, cheap tubular steel (actually hollow steel tubes with nothing but air in them) or lighter steel or aluminum alloys.
Ntau tus neeg yuav xav tias lub tsheb kauj vab thav duab ua los ntawm txhuas raj yuav tsis muaj zog dua li cov ncej hlau. Qhov no tsuas yog muaj tseeb yog tias cov hlab ntsha zoo sib xws. Qhov tseeb, txhua lub tsheb kauj vab yuav tsum muaj zog txaus los txhawb qhov hnyav hnyav. Yog li ntawd, lub tsheb kauj vab txhuas yuav siv lub taub loj dua lossis cov raj tuab dua li lub tsheb kauj vab hlau.
Yuav ua li cas blub tsheb kauj vabua haujlwm
Txij li thaum txhua lub log muaj 24 spokes, hauv kev xyaum lawv dais qhov hnyav tsis sib xws. Tshwj xeeb tshaj yog, cov spokes nyob ze ntawm lub ntsug yog raug rau ib tug ntau dua load dua lwm yam spokes thaum lub log tig.
The closer the spokes move to the vertical, the more deformation it is subjected to. The load that each spoke is subjected to increases and decreases dramatically with each revolution of the wheel. After thousands of such cycles over and over again, one of the spokes may fail. That causes an immediate increase in the load on the remaining spokes. As such, they are more likely to be damaged by a kind of "domino" effect. As a result, the bicycle wheel will be warped.
A wheel and the axis it rotates around is a good example of the "simple machine" that scientists often refer to. Bicycle wheels are typically over 50 centimeters (20 inches) in diameter, taller than most car wheels, and it multiplies force or speed depending on how you spin it. The higher the wheels, the faster they spin. That is why racing bike wheels have the largest diameter (about 70cm or 27.5 inches).
Yuav ua li castsheb kauj vab iav ua haujlwm
The gears are chain-linked so you can ride faster (down a straight line) or easier (uphill). It is also an example of a simple machine. Gears can make amazing changes in your speed. For example, if the gear ratio on a race car is 5:1, one lap of the pedals will take you about 35 feet (10m) on the street. When you ride a bike, the pedaling force you generate causes the bike's gears to turn the rear wheel.
This deceptively simple two-wheeled machine harnesses momentum, force and friction and converts that energy into the power that gets the rider to his destination. Whether you're teaching the physics of a bicycle or a class with a simple machine, there are many exercises you can learn on the bike.
