Mechanical Devices
Gbogbo ọrọ náà
Pick up a pair of nail clippers. Your thumb pushes down with a force you could apply all day, and at the other end two blades cut through a material that would blunt a kitchen knife. Nothing in the clippers generates any force at all. Every newton at the blades came from your thumb, and the clippers simply rearranged it, trading a long movement for a short one and a small force for a large one.
That trade is what mechanical devices do, and it is the whole of this lesson. You will learn the functions of mechanical devices that produce linear, rotary, reciprocating and oscillating movements, and how they change the magnitude and direction of force. You will meet levers of the first, second and third classes, linkages including bell cranks and push and pull arrangements, and rotary systems: cams and followers, simple gear trains, and pulleys and belts. You will calculate mechanical advantage, gear ratios and output speeds, and you will choose between three ways of doing the same job on a real product. This is core technical principles content, examined in Section A of Paper 1, where it supplied question 8 of the specimen paper.
Ebumnobi
- The functions of mechanical devices to produce linear, rotary, reciprocating and oscillating movements.
- Changing magnitude and direction of force
- Levers:
- levers, first, second and third classes.
- Linkages:
- bell cranks
- push/pull.
- Rotary systems:
- cams and followers
- simple gear trains
- pulleys and belts.
Maapụ uche
E seela isiokwu a ka ị hụ otu echiche si ejikọta.
Mepee maapụ uche na ngwa
Akwụkwọ Ọmụmụ
Ndetu Nkuzi Zuru Ezu di na Ngwa Green Bridge
Nweta ngwa Green Bridge CBT na ekwenti gi ma o bu kompiuta maka ulo akwukwo IGCSE zuru oke: akwukwo ule ndi gara aga, usoro nyocha, eserese uche, kaadi omumu na nkuzi olu.
Nnyocha Ọmụmụ
Ekele diri gi maka imecha ihe karịrị na Mechanical Devices. Ugbu a na ị na-enyochakwa isi echiche na echiche ndị dị mkpa, ọ bụ oge iji nwalee ihe ị ma. Ngwa a na-enye ụdị ajụjụ ọmụmụ dị iche iche emebere iji kwado nghọta gị wee nyere gị aka ịmata otú ị ghọtara ihe ndị a kụziri.
Ị ga-ahụ ngwakọta nke ụdị ajụjụ dị iche iche, gụnyere ajụjụ chọrọ ịhọrọ otu n’ime ọtụtụ azịza, ajụjụ chọrọ mkpirisi azịza, na ajụjụ ede ede. A na-arụpụta ajụjụ ọ bụla nke ọma iji nwalee akụkụ dị iche iche nke ihe ọmụma gị na nkà nke ịtụgharị uche.
Jiri akụkụ a nke nyocha ka ohere iji kụziere ihe ị matara banyere isiokwu ahụ ma chọpụta ebe ọ bụla ị nwere ike ịchọ ọmụmụ ihe ọzọ. Ekwela ka nsogbu ọ bụla ị na-eche ihu mee ka ị daa mba; kama, lee ha anya dị ka ohere maka ịzụlite onwe gị na imeziwanye.
- A windscreen wiper blade moves backwards and forwards along an arc. This motion is described as A. linear. B. oscillating. C. reciprocating. D. rotary. Answer: B
- In which class of lever is the load always between the fulcrum and the effort? A. First class B. Second class C. Third class D. All classes Answer: B
- A driver gear of 12 teeth meshes with a driven gear of 36 teeth. The driver turns at 600 revolutions per minute. What is the output speed? A. 100 revolutions per minute B. 200 revolutions per minute C. 1,800 revolutions per minute D. 3,600 revolutions per minute Answer: B
- Which cam gives the follower a period of dwell in every revolution? A. An eccentric cam B. A pear cam C. A snail cam D. No cam can Answer: B
- An idler gear is added between a driver and a driven gear. What is its effect? A. It doubles the output speed B. It halves the output torque C. It reverses the direction of the driven gear without changing the ratio D. It has no effect at all Answer: C
Rue ajuju ndi a n'ime ngwa ahu
Rue ajuju ndi a n'ime ngwa ahu
Akwụkwọ A Na-atụ Aro
Meecha Ajụjụ Ule Ọmarịcha
Ị chọrọ ime ajụjụ ule ọmarịcha gbasara Mechanical Devices? Budata ngwa Green Bridge CBT iji nweta ajụjụ ule ọmarịcha na nyocha zuru ezu gbasara isiokwu a.
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