3 ngā pātai mō te whārite pūmau puna
1. He 10 cm te roa o tētahi puna e whakatārewatia ana. I te pito whakatārewatia, ka whakatārewatia he taumaha 200 karamu kia 11 cm te roa o te puna. Mena ko te karamu = 10 m/s² , he aha te pūmau kaha o te puna?
Mōhiotia:
Ko te roa tīmatanga o te puna (y 1 ) = 10 cm = 0.10 m
Ko te roa whakamutunga o te puna (y 2 ) = 11 cm = 0.11 m
Te huringa roa o te puna (Δy) = 0.11 – 0.10 = 0.01 mita
Te papatipu o te kawenga (m) = 200 karamu = 0.2 kg
Taumaha kawenga (w) = mg = (0,2)(10) = 2 Newton
E hiahiatia ana: Pūmau puna (k)
Rongoā:
Tātai pūmau puna:
F = k Δy
k = F / Δy = 2 / 0,01 = 200 / 1 = 200 Ngā Newton/mita
2. Ka taea te totoro i tētahi puna kia totoro ake mā te 10 cm me te kaha pūmanawa o te 0.5 Joule. He aha te pūmau puna?
Mōhiotia:
Ko te tāpiritanga o te roa o te puna (Δy) = 10 cm = 0.1 mita
Pūngao pūmanawa o te puna (EP) = 0.5 Joules
E hiahiatia ana: Pūmau puna (k)
Rongoā:
Ka tatauhia te pūmau puna mā te whakamahi i te tātai Pūngao Pūmanawa Puna:
EP = ½ k Δy 2
2 EP = k Δy 2
2 (0,5) = k (0,1) 2
1 = k (0,01)
k = 1 / 0,01 = 100 / 1 = 100 Ngā Newton/mita
3. Ka whakanuia te roa o tētahi puna e tōia ana me te kaha o te 100 N mā te 5 cm. Tātaihia te pūmau puna.
Mōhiotia:
Te kaha (F) = 100 N
Te pikinga o te roa o te puna (Δx) = 5 cm = 0.05 m
E hiahiatia ana: Pūmau puna (k)
Rongoā:
F = k Δx
k = F / Δx = 100 / 0,05 = 10.000 / 5 = 2000 Newton/mita
