Me pēhea te tatau i te pūngao nekeneke
He ariā nui te pūngao i roto i te ahupūngao e whakamārama ana i te kaha o tētahi mea ki te mahi. I roto i te oranga o ia rā, he maha ngā wā ka tūtaki tātou ki te pūngao i roto i ngā momo āhua - mai i te pūngao wera, te pūngao hiko, ki te pūngao nekeneke. Ko tētahi o ngā momo pūngao ngāwari ki te mātakitaki ko te pūngao nekeneke, te pūngao kei roto i tētahi mea nā tōna nekehanga. Ka matapakihia e tēnei tuhinga te whakamāramatanga o te pūngao nekeneke, tōna tauira, me pēhea te tatau, ngā tauira, me tōna whanaungatanga ki ngā āhuatanga o te ao tūturu.
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Te Mārama ki te Pūngao Kinetic
Ko te pūngao nekeneke te pūngao kei roto i tētahi mea nā tōna nekehanga. Ka tere ake te neke o tētahi mea, ka nui ake tōna pūngao nekeneke. Haunga te tere, ka pāngia hoki te pūngao nekeneke e te taumaha o te mea. Ka nui ake te pūngao nekeneke o tētahi mea e neke ana he taumaha nui tōna i tētahi mea he iti tōna taumaha i te tere ōrite.
Tauira māmā:
– He iti noa te pūngao nekeneke o te pōro e pōturi ana te hurihuri.
– He nui ake te pūngao nekeneke o te motuka tere e neke ana, nō reira he nui ake te pānga mēnā ka puta he tukinga.
Ko te pūngao nekeneke he wāhanga o te pūngao miihini, me te pūngao pūmanawa. I roto i te maha o ngā take ahupūngao, ka taea e te pūngao miihini te huri i te āhua, hei tauira, ka huri te pūngao pūmanawa ki te pūngao nekeneke ina taka tetahi mea.
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Tātai Pūngao Kinetic
Ko te tātai pūngao nekeneke mō tētahi mea e neke ana i te rārangi tika (e neke ana i te rārangi tika) ko:
\[
E_k = \frac{1}{2} mv^2
\]
Ngā Mōhiohio:
– \(E_k\) = Pūngao nekeneke (Joule, J)
– \(m\) = te papatipu o te mea (kirokaramu, kg)
– \(v\) = tere o te mea (mita ia hekona, m/s)
Ko te waeine o te pūngao nekeneke ko te Joule (J), he rite te āhua ki:
\[
1 \text{ J} = 1 \text{ kg} \cdot \text{m}^2/\text{s}^2
\]
He aha i tapawhāhia ai te tere? Nā te mea e pā ana te pūngao nekeneke ki te mahi e hiahiatia ana hei whakatere i tētahi mea mai i te okioki ki tētahi tere. Ina piki rua te tere, ka piki whā te pūngao nekeneke—he mea nui kia mārama tēnei kia kore ai e whakaaro hē he hononga rārangi i waenga i te tere me te tere.
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Ngā Hipanga hei Tātai i te Pūngao Kinetic
Anei tētahi huarahi pūnaha hei tatau i te pūngao nekeneke:
1. Tāutuhia te papatipu o te mea (\(m\))
Kia tino tika te papatipu i roto i ngā kirokaramu (kg). Mena kei roto tonu i ngā karamu te papatipu, hurihia tuatahitia:
\[
1000 karamu = 1 kg
\]
2. Tāutuhia te tere o te mea (\(v\))
Kia tika te tere i roto i te m/s. Mena kei roto tonu te tere i te km/h, hurihia ki te m/s mā te whakamahi i te tātai:
\[
v(\kākau{m/h}) = \frac{v(\kākau{km/h})}{3{,}6}
\]
Nā te mea ko te 1 km = 1000 m me te 1 hāora = 3600 s, ko te tauwehenga tahuritanga ko te 3,6.
3. Tāruatia te tere (\(v^2\))
Tātaihia \(v \whakareatia ki te v\). He taahiraa tēnei e arahi pinepine ana ki ngā hapa mēnā kāore e tūpato.
4. Whakauruhia ki te tātai
Whakamahia:
\[
E_k = \frac{1}{2} mv^2
\]
5. Tuhia te hua ki ngā Joules (J)
Kia tika ngā waeine. Mena he tino nui te hua, ka taea te whakaatu i roto i te kilojoules (kJ) me te megajoules (MJ) mā te whakamahi i te huringa e whai ake nei:
– 1 kJ = 1000 J
– 1 MJ = 1.000.000 J
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Tauira o te Tātaitanga Pūngao Kinetic
Tauira 1: Pōro hurihuri
Kei te neke tētahi pōro, e 2 kg te taumaha, i te tere o te 3 m/s. Tātaihia tōna pūngao nekeneke.
E mōhiotia ana:
– \(m = 2\) kg
– \(v = 3\) m/s
\[
E_k = \frac{1}{2} \cdot 2 \cdot 3^2
\]
\[
E_k = 1 \cdot 9
\]
\[
E_k = 9 \text{ J}
\]
Nō reira, ko te pūngao nekeneke o te pōro he 9 Joules.
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Tauira 2: Kei te neke te motuka
Kei te neke tētahi motuka he 1200 kg te taumaha i te tere o te 20 m/s. He aha tōna pūngao nekeneke?
E mōhiotia ana:
– \(m = 1200\) kg
– \(v = 20\) m/s
\[
E_k = \frac{1}{2} \cdot 1200 \cdot 20^2
\]
\[
E_k = 600 \cdot 400
\]
\[
E_k = 240000 \text{ J}
\]
Ko te pūngao nekeneke o te motuka he 240.000 Joules, 240 kJ rānei.
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Tauira 3: Tahurihia te km/h ki te m/s
Kei te tere te motopaika, he 150 kg te taumaha, i te tere o te 72 km/h. Tātaihia tōna pūngao nekeneke.
Hipanga 1: Tahurihia te tere
\[
v = \frac{72}{3{,}6} = 20 \text{ m/s}
\]
Hipanga 2: Tātaihia te pūngao nekeneke
\[
E_k = \frac{1}{2} \cdot 150 \cdot 20^2
\]
\[
E_k = 75 \cdot 400
\]
\[
E_k = 30000 \text{ J}
\]
Nō reira, ko te pūngao nekeneke o te mōta he 30.000 Joules, arā, 30 kJ.
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Ngā Take e Pā Ana ki te Pūngao Kinetic
Mai i te tātai \(E_k = \frac{1}{2}mv^2\), e rua ngā āhuatanga matua e kitea ana:
1. Taumaha (m)
He rite tonu te kaha nekeneke ki te papatipu. Mēnā ka takiruahia te papatipu, ka takirua anō hoki te kaha nekeneke (i te tere pumau).
2. Tere (v)
He rite tonu te kaha nekeneke ki te tapawhā o te tere. Mēnā ka rua te tere, ka whā te kaha nekeneke. Koia te take ka nui te pānga o te whakanui ake i te tere o te waka ki te mōrearea o ngā aituā me te tawhiti o te aukati.
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Pūngao Kinetic i te Oranga o Ia Rā
Ehara te ariā o te pūngao nekeneke i te ariā noa iho; he whānuitia te whakamahinga i roto i ngā mara maha:
– Te haumaru taraiwa: Ka tere ake te waka, ka nui ake te pūngao me "marara" i te wā e pēhi ana, kia nui ake ai te tawhiti pēhi.
– Ngā Hākinakina: He nui ake te pūngao nekeneke o te pōro e whiua teretia ana, nō reira he kaha ake te whiu (pērā i te whutupaoro, i te pēihipora rānei).
– Te hangarau me te mīhini: Ka whakaarohia te pūngao nekeneke i roto i te hoahoa o ngā mīhini, ngā wira rere, me ngā pūnaha aukati kia mōhio ai kei te haumaru, kei te whai hua hoki ngā taputapu.
– Te whakaputa hiko: I roto i ngā tāpine hau, ka hurihia te pūngao nekeneke o te hau hei pūngao miihini, kātahi hei pūngao hiko.
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Ngā Hapa Noa i te Tātaitanga o te Pūngao Kinetic
Ko ētahi hapa noa:
1. Kaua e whakarerekē i ngā waeine (hei tauira, ko te kg he karamu tonu, ko te tere he km/haora tonu).
2. I wareware ki te tapawhā i te tere kia iti rawa ai te hua i te mea e tika ana.
3. Te tātai hē i ngā mahi pāngarau, inā koa he nui ngā tau.
4. Te pohehe i te papatipu hei taumaha. He rerekē te papatipu (kg) i te taumaha (N).
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Whakamutunga
Ko te pūngao nekeneke ko te pūngao kei roto i tētahi mea nā te mea e neke ana, ā, ka taea te tatau mā te whakamahi i te tātai:
\[
E_k = \frac{1}{2} mv^2
\]
He tino māmā te tatau: kia tino tika te papatipu i roto i te kg, ā, ko te tere i roto i te m/s, tapawhāhia te tere, kātahi ka mono ki te tātai. Ko te mea nui kia mārama ko te tere o te piki haere o te pūngao nekeneke i te pikinga o te tere nā te mea e whakawhirinaki ana ki \(v^2\). Mā te mārama ki te tatau i te pūngao nekeneke, ka taea e tātou te tātari ngāwari ake i ngā āhuatanga ā-tinana, mai i te nekehanga o ngā mea ngāwari ki ngā pūnaha waka me ngā mīhini o te ao tūturu.
Ki te hiahia koe, ka taea hoki e au te hanga i ētahi atu pātai whakaharatau me ngā whakamārama (hei tauira, 10 ngā pātai mai i te ngāwari ki te uaua) hei whakapakari i tō māramatanga.
