Basa rakaitwa nechisimba
1.1 Tsanangudzo yeBasa
Kana ukasundira bhuku pamusoro petafura kusvika bhuku rabviswa, unoudzwa kuti waita basa pabhuku. Kana chinhu chikawira pasi nekuda kwekukweverwa nesimba regiravhiti, simba regiravhiti rinonzi rashanda pachinhu chacho. Kusiyana neizvi, kana ukasundira chinhu nesimba rako rese kusvika pakudikitira zvakanyanya, asi chinhu chacho chisingafambi zvachose, unonzi hauna kuita basa pachinhu chacho. Muhupenyu hwezuva nezuva, vanhu vanogona kuti waita basa rakaoma nekusundira chinhu asi muFizikisi, hauite basa pachinhu chacho nekuti hapana kuchinja kwechinhu chacho.
Basa pachinhu rinogona kuitwa nesimba risingaperi (huwandu negwara rayo hazvichinji) kana simba rinoshanduka (huwandu negwara rayo zvinosiyana). Muenzaniso wesimba rine huwandu negwara risingaperi isimba rinokwevera, rinoshanda pachinhu kana chinhu chiri pedyo nepasi. Kana chinhu chiri mukudonha kwakasununguka pedyo nepasi, huwandu negwara rekukwira kwekukurumidza kwekuwa kwechinhu hazvichinji nekuti huwandu negwara resimba rinokwevera rinokurumidzisa chinhu hazvichinji. Muenzaniso wesimba rine huwandu husingachinji (asi negwara risingaperi) isimba rechitubu . Mumwe muenzaniso iroketi rinokandwa muchadenga kana kudzokera pamusoro penyika. Kana roketi yaburitswa, huwandu hwesimba rinokwevera rinoshanda pariri hunochinja zvichienderana nedaro repakati penyika.
1.1.1 Basa rinoitwa nemauto anoramba aripo
Pamasvomhu, basa rinoitwa nesimba risingaperi pachinhu rinotsanangurwa sekutama kwakawedzerwa nesimba kana chikamu chesimba chine gwara rakafanana nekutama kwechinhu. Tarisa chinhu chiri pamusoro penzvimbo yakatsetseka isina kusimba ine kutamiswa kurudyi kunokonzerwa nesimba rekusundidzira (F).
Mufananidzo 1. (Kumusoro) Kutungamira kwekutama kwechinhu kwakafanana nekwesimba F. (Pasi) Kutungamira kwekutama kwechinhu kwakafanana nechikamu chesimba F munzira yakatwasuka (F cos).
Basa rinoitwa nesimba rekusundidzira (F) nderekuti:
W = (F)(s)(cos θ) = F s (cos 0) = F s (1)
W = F s
Basa rinoitwa nechikamu chesimba F munzira yakatwasuka (F cos θ) nderinotevera:
W = (F cos θ)(s)(cos 0) = (F cos )(s)(1)
W = F s cos θ
Basa rinoitwa ne kinetic frictional force (f k ) nderekuti:
W = (f k )(s)(cos 180) = (f k )(s)(-1)
W = – (f k )(s)
Basa rinoitwa nechisimba chemazuva ose (N) nderinotevera:
W = (N)(s)(cos 90) = (N)(s)(0) = 0
Basa rinoitwa nehukuru (w) nderekuti:
W = (w)(s)(cos 90) = (w)(s)(0) = 0
Tsananguro: W = basa, s = huwandu hwekutama, θ = kona iri pakati pesimba nekutama.
Mufananidzo 2.
(a) Chinhu chiri mukudonha kwakasununguka. Huremu huri munzira imwecheteyo nekufamba (b) Chinhu chinofamba chakamira kumusoro. Kutungamira kwehuremu kwakatarisana nekutungamira kwekufamba.
Mumuenzaniso wapfuura, basa rinoitwa nehuremu (w) rine kukosha kwe zero sezvo divi rehuremu hwechinhu rakanangana nedivi rekufamba kwechinhu. Zvinofanira kucherechedzwa kuti basa rinoitwa nehuremu harizove ne kukosha kwe zero kana divi rehuremu rakafanana kana kuti rakapesana nedivi rekufamba kwechinhu.
Basa rinoitwa nehuremu (w) pachinhu chiri mukudonha kwakasununguka rinoratidzwa mumufananidzo a nderinotevera:
W = F s (cos θ) = wh (cos 0) = wh (1) = wh = mgh
Basa rinoitwa nehuremu (w) pachinhu chiri kufamba chakamira kumusoro sezvakaratidzwa pamufananidzo b nderinotevera:
W = F s (cos θ) = wh (cos 180) = wh (-1) = – wh = – mgh
Tsananguro: w = huremu (Newton), h = kureba (mita), m = huremu (kg), g = kukurumidza kwegiravhiti (mita pasekondi imwe neimwe).
Zvichienderana netsananguro yapfuura, mhedziso dzinotevera dzinotorwa: Chekutanga, kana chinhu chisina kusuduruka, simba rinoshandiswa pachinhu harishande. Kana s = 0, W = 0; Chechipiri, kana simba rikaita kona yakapihwa yakanangana nekusuduruka kwechinhu , chikamu chesimba chinogovana divi rakafanana nerekusuduruka kwechinhu ndicho chinoshanda pachinhu; Chechitatu, simba riri munzira yakatarisana negwara rekusuduruka kwechinhu richagadzira kona ye90 o . Cos 90 = 0; Chechina, basa rinogona kuva nechiratidzo chakanaka kana chakaipa. Kana simba riri munzira imwechete nekusuduruka kwechinhu uye rikaita kona ye0 o , rinoita basa rakanaka pachinhu. Kusiyana neizvi, kana simba riine gwara rakapesana negwara rekusuduruka kwechinhu uye rikaita kona ye180 o , rinoita basa risina kunaka pachinhu.
Mufananidzo 3. Simba (F) – girafu yekutama (s). Basa rakaenzana nenzvimbo ine mumvuri.
Basa rinoitwa nesimba risingaperi pachinhu kana chinhu chacho chiri kutama rakaenzana nenzvimbo ine mumvuri mugirafu resimba (F) - chinzvimbo (s).
Basa rinotaridzwa seW (mabhii makuru), uye huremu hunotaridzwa sew (mabhii madiki). Chikamu cheSI chebasa iNewton ∙ meter (N m). Rakaenzana neJoule, rakapfupikiswa seJ.
Yakatumidzwa zita iri kuratidza ruremekedzo kuna chiremba wekuBritain wemuzana remakore rechi19 , James Prescott Joule.
Muenzaniso wemubvunzo 1: Basa rinoitwa nesimba risingaperi
Chinhu chiri pamusoro pepasi risingakweshe. Pachinhu chacho panoiswa simba re10 N, zvichiita kona yemadhigirii makumi matatu ichipesana nepasi. Kana chinhu chikafamba daro remita imwe, simba riri pachinhu chacho rinoitwa basa rakawanda sei?
Solution:
Inozivikanwa: F = 10 N, s = mita imwe
Kudiwa: Basa (W)
W = (F)(s)(cos 30 o ) = (10 N)(1 m)(1/2 √ 3) = 5 √ 3 N m
Muenzaniso wemubvunzo wechipiri: Kushanda nesimba risingaperi
Kokonati ine huremu hwe 0.2 kg inodonha kubva pakakwirira kwemamita gumi kubva pamusoro pevhu. Kana simba rekukwevera pasi riri 10 m/s 2 , basa rakawanda sei rinoitwa nehuremu pakokonati?
Solution:
Inozivikanwa: m = 0.2 kg, h = 10 m, g = 10 m/s 2
Zvinodiwa: Basa (W) nehuremu (w)
W = F s = wh = mgh = (0.2 kg)(10 m/s 2 )(10 m) = 20 kg m 2 /s 2 = 20 N m = 20 Joules
1.1.2 Basa nemasimba anoshanduka-shanduka
Muenzaniso wesimba rinoshanduka isimba rechitubu. Huwandu hwesimba rechitubu hunochinja nguva dzose. Saka, basa rinoitwa nesimba rechitubu pachinhu harigone kuverengerwa uchishandisa fomura yebasa remasimba asingachinji (W = F s cos θ). Kana chitubu chakatambanudzwa, chitubu chakatambanudzwa zvakanyanya, simba rekudhonza rinodiwa kuti chitubu chitambanudzwe zvikuru. Uye kana chitubu chakadzvanywa, chitubu chakadzvanywa zvakanyanya, simba rekusundidzira rinodiwa zvikuru. Kana chitubu chakadzvanywa kana kutatamurwa, simba rechitubu rinoshanduka kubva pa0 (x = 0) kusvika pahuwandu hwakanyanya (F = kx). Saka, huwandu hwesimba rechitubu hunoverengerwa uchishandisa avhareji. Avhareji yesimba rechitubu ndeiyi:
Basa rinoitwa nechisimba chechitubu pachinhu nderinotevera:
W = basa, x = Δx = kutsauka kwechitubu (mita), F = simba rechitubu (Newton).
Muenzaniso wemubvunzo 3: Basa nesimba rinoshanduka
Pachitubu pane huremu hwakasungirirwa hune huremu hwe1 kg, saka chitubu chinotambanuka ne2 cm. Kana kukurumidza kwegiravhiti kuri 10 m/s 2 , sarudza (a) chitubu chisingachinji (b) basa rinoitwa nesimba rechitubu pahuremu.
Solution:
Inozivikanwa: m = 1 kg, g = 10 m/s 2 , x = Δx = 2 cm = 0.02 m.
(a) chitubu chinoramba chiripo
(b) basa rakaitwa nechisimba chemvura pamusoro pehuremu
W = -1/2 kx 2 = -1/2 (500)(0.02) 2 = – (250)(0.0004) = -0.1 Joule
Basa rinoitwa nesimba rechitubu pahuremu harina kukosha sezvo gwara resimba rechitubu rakapesana negwara rekusimuka kwehuremu (simba rechitubu riri kumusoro, huremu huri pasi).
1.2 Basa reNet kana Basa neNet Force
Kana paine simba rimwe chete rinoshanda pachinhu kana chinhu chacho chiri kukanganiswa, basa rinoitwa nesimba remagetsi rinoenzana nebasa rinoitwa nesimba. Semuenzaniso, kana chinhu chiri mukudonha kwakasununguka uye kurambidzwa kwemhepo kukasateererwa, simba chete rinoshanda pachinhu chacho isimba remagetsi rinokwevera pasi. Muchiitiko ichi, simba remagetsi rinoshanda pachinhu chacho isimba remagetsi rinokwevera pasi (ona mufananidzo 2).
W net = W simba regiravhiti
Kana mamwe masimba ari kushanda pachinhu kana chinhu chacho chiri kukanganiswa, basa rinoitwa nemasimba emagetsi rakaenzana nebasa remagetsi rinoitwa nemasimba ese ari kushanda pachinhu chacho (ona mufananidzo 1).
W net = W 1 + W 2 + W 3 + W 4
Basa rinoitwa ne net force pachinhu rinogonawo kuverengwa nekutsvaga net force kutanga wozoiwedzera nehuwandu hwekusanduka.
W = ΣF s
Muenzaniso wemubvunzo wechi4: Network
Bhokisi risingamire riri pamusoro pevhu rinosundirwa nesimba re20 N kusvika bhokisi rafamba mita imwe kure. Kana simba rekusundidzira riri munzira imwecheteyo nekutama kwebhokisi uye pabhokisi richishanda simba rekukweshana re2 N, sarudza huwandu hwebasa rinoitwa nesimba remambure pabhokisi.
Solution:
Inozivikanwa: F = 20 N, f k = 2 N, s = 1 m
W 1 = F s = (20 N)(1 m) = 20 Nm = 20 Joules
W 2 = f ks = – (2 N)(1 m) = – 2 Nm = – 2 Joules
Basa repaIndaneti kana basa rinoitwa nechisimba chepamhepo
W mambure = W 1 – W 2 = 20 J – 2 J = 18 J
Muenzaniso wemubvunzo 4) Simba rekukwesha (F) rinoita basa rakanaka, simba rekukweshana rekinetic (f k ) rinoita basa risina kunaka
