Mechanical Devices
Akopọ
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.
Awọn Afojusun
- 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.
Àwòrán ọpọlọ
A ti ṣe àwòrán kókó yìí kí o lè rí bí àwọn èrò ṣe so pọ̀.
Ṣí àwòrán ọpọlọ nínú áàpù
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Gba ohun èlò Green Bridge CBT sórí fóònù tàbí kọ̀mpútà rẹ fún gbogbo ilé ìkàwé IGCSE: ìwé ìdánwò àtijọ́, ìlànà ìdíwọ̀n, àwòrán èrò, káàdì ìkẹ́kọ̀ọ́ àti ẹ̀kọ́ ohùn.
Ìdánwò Ẹ̀kọ́
Oriire fun ipari ẹkọ lori Mechanical Devices. Ni bayi ti o ti ṣawari naa awọn imọran bọtini ati awọn imọran, o to akoko lati fi imọ rẹ si idanwo. Ẹka yii nfunni ni ọpọlọpọ awọn adaṣe awọn ibeere ti a ṣe lati fun oye rẹ lokun ati ṣe iranlọwọ fun ọ lati ṣe iwọn oye ohun elo naa.
Iwọ yoo pade adalu awọn iru ibeere, pẹlu awọn ibeere olumulo pupọ, awọn ibeere idahun kukuru, ati awọn ibeere iwe kikọ. Gbogbo ibeere kọọkan ni a ṣe pẹlu iṣaro lati ṣe ayẹwo awọn ẹya oriṣiriṣi ti imọ rẹ ati awọn ogbon ironu pataki.
Lo ise abala yii gege bi anfaani lati mu oye re lori koko-ọrọ naa lagbara ati lati ṣe idanimọ eyikeyi agbegbe ti o le nilo afikun ikẹkọ. Maṣe jẹ ki awọn italaya eyikeyi ti o ba pade da ọ lójú; dipo, wo wọn gẹgẹ bi awọn anfaani fun idagbasoke ati ilọsiwaju.
- 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
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Ṣe o fẹ ṣe adaṣe awọn ibeere idanwo adaṣe nipa Mechanical Devices? Ṣe igbasilẹ ohun elo Green Bridge CBT lati wọle si awọn ibeere idanwo adaṣe ati awọn ayẹwo adaṣe kikun fun koko-ọrọ yii.
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