Ngā tauira o ngā pātai mahi mō te pūngao nekeneke me te ahupūngao

5 Ngā tauira o ngā pātai mahi mō te pūngao nekeneke me te ahupūngao

1. He motuka he 5000 kg te taumaha e tū ana i te tīmatanga, kātahi ka neke i te tere o te 20 m/s. Tātaihia te mahi katoa i mahia ki te motuka...
Kōrero
E mōhiotia ana :
Taumaha (m) = 5000 kg
Te tere tīmatanga (v_o) = 0 m/s (i te tīmatanga ka tū te motuka)
Te tere whakamutunga (v_t) = 20 m/s
I pātaihia Te whakapau kaha katoa
Whakautu :
Te ariā pūngao mahi-nekeneke e kī ana ko te mahi katoa he rite ki te huringa o te pūngao nekeneke. Mā te pāngarau:
Te whakapau kaha katoa:
W_katoa = ½ m (v_t² -v_o²)
W_katoa = ½ (5000)(20² - 0²)
W_katoa = (2500)(400 – 0)
W_katoa = (2500)(400)
W_katoa = 1000.000
Ko te tapeke o te mahi he 1000.000 Joules.

2. I te tīmatanga, ka neke te mea he 10 kg te taumaha i te tere o te 5 m/s. I muri tata iho, ka neke te mea i te tere o te 10 m/s. Tātaihia te mahi katoa i mahia ki te mea.
Kōrero
E mōhiotia ana :
Papatipu o te mea (m) = 10 kg
Te tere tīmatanga (v_o) = 5 m/s
Te tere whakamutunga (v_t) = 10 m/s
I pātaihia : te whakapau kaha katoa
Whakautu :
Te whakapau kaha katoa:
Ko te tapeke o te mahi he 375 Joules.

3. Kei te neke tētahi waka he 2000 kg te taumaha i te tere whakapae o te 10 m/s. Kātahi ka whakaitihia e te taraiwa te tere o te waka ki te 5 m/s. Ko te mahi i mahia e te taraiwa i runga i te waka ko...
Kōrero
E mōhiotia ana :
Taumaha o te motuka (m) = 2000 kg
Te tere tīmatanga (v_o) = 10 m/s
Te tere whakamutunga (v_t) = 5 m/s
I pātaihia : te whakapau kaha katoa
Whakautu :
Te whakapau kaha katoa:
Ko te tapeke o te mahi he 75.000 Joules.
Ko te tohu kino ko te kaha e pā ana ki te motuka kei te taha ke atu i te nekehanga o te motuka. Ko te mahi kino ko te tikanga hoki ka heke te kaha nekeneke o te motuka.

4. I te tīmatanga, ka tū tonu tētahi waka he 1 tana te taumaha. I muri tata iho, ka neke i te tere o te 10 m/s. Ko te nui o te mahi e mahia ana e te mīhini o te waka ko...
A. 1.000 Joules
B. 10.500 Joules
C. 15.000 Joule
D. 25.000 Joule
E. 50.000 Joule
Kōrero:
E mōhiotia ana :
m = 1 tana = 1000 kg, v_o = 0 m/s, v_t = 10m/s
I pātaihia :
Ngā Mahi (W)?
Whakautu :
Mahi = huringa o te pūngao nekeneke

Te huringa o te pūngao nekeneke :
= ½ m(v_t² -v_o²) = ½ (1000)(100 – 0) = ½ (1000)(100) = 50.000 kg m²/s² = 50.000 Joule
Nō reira, ko W = 50.000 Joule
Ko te whakautu tika ko E.

5. He tēpu he 10 kg te taumaha e tū ana i te tīmatanga i runga i te papa maeneene, kātahi ka panaia mō te 10 hēkona kia neke tika ai me te whakaterenga o te 2 m/s.²Ko te nui o te mahi i puta ko…
A. 2000 Joules
B. 3000 Joules
C. 6000 Joule
D. 8000 Joule
E. 9000 Joule
Kōrero:
E mōhiotia ana :
m = 10 kg, t = 10 hēkona, v_o = 0, a = 2 m/s², roto_t = ?
I pātaihia :
Ngā Mahi (W)?
Whakautu :
Tātaihia te tere whakamutunga (v_t):
v_t = v_o + i = 0 + (2)(10) = 20 m/s

Mahi = huringa o te pūngao nekeneke

Te huringa o te pūngao nekeneke :
= ½ m(v_t² -v_o²) = ½ (10)(400 – 0) = ½ (10)(400) = ½ (4000) = 2000 Joule
Nō reira, ko W = 2000 Joule
Ko te whakautu tika ko A.