Lipotso tse 5 tsa mehlala ho phaphamala
1. Boima ba mojaro o moeeng ke 3 N, boima ba mojaro o metsing ke 2,8 N. Metsi a sebelisa matla a makae ho phaphamala mojaro?
Puisano:
2. Tšepe e boima ba 100 N ha e lekanngoa moeeng le 80 N ha e lekanngoa metsing. Bophahamo ba tšepe ke bokae?
Puisano:
Hoa tsebahala hore:
w = 100 N
moea o le mong = 80 N
O botsitse: Bophahamo ba tšepe ?
Bongata ba tšepe e qoelitsoeng ka metsing bo lekana le bongata ba metsi a tlositsoeng.
3. Lefika le na le boima ba lik'hilograma tse 10. Ha le lekanngoa ka metsing, boima ba lefika ke lik'hilograma tse 8,2. Boima ba lefika ke bofe?
Puisano:
Hoa tsebahala hore:
g = 9,8 m/s2
m = 10 kg
metsi = 8,2 kg
Botsitswe: Botenya ba lefika ( ?
Karabo:
4. Boloko ba lepolanka bo bolelele ba 2,5 m, bophara ba 0,5 m le botenya ba 0,4 m. Haeba patsi e qoelitsoe metsing, 'me boima ba metsi e le 1000 kg/m3 , joale boholo ba khatello e nyolohang ke... (g = 10 N/kg)
A. 400 N
B. 500 N
C. 4.000 N
D. 5.000 N
Puisano
Hoa tsebahala hore:
Bophahamo ba cuboid (V) = bolelele x bophara x botenya = 2,5 x 0,5 x 0,4 = 0,5 m3
Boima ba metsi (ρ) = 1000 lik'hilograma / m3
Ho potlaka ka lebaka la matla a khoheli (g) = 10 N/kg
O botsitse: Matla a maholo a ho phaphamala
Karabo:
Foromo ea matla a ho thothomela:
F= ρ g V
Tlhaloso: F = matla a ho phaphamala, ρ = Botenya, g = ho potlaka ka lebaka la matla a khoheli, V = bophahamo ba modumo
Meqolo eohle ea lintho tse qoelitsoeng ka metsing e le hore matla a ho phaphamala a baloe ho sebelisoa mokhoa o ka holimo.
F = (1000)(10)(0,5) = (1000)(5) = 5000 Newtons
Karabo e nepahetseng ke D.
5. Boima ba ntho e moeeng ke 100 N, ebe e kenngoa ka har'a mokelikeli e le hore bophahamo ba eona bo eketsehe ka 1,5 m3Haeba boima bo itseng ba mokelikeli e le 10 N/m3, joale boima ba ntho e ka har'a mokelikeli ke...
A. 1.500 N
B. 115 N
C. 85 N
D. 6,7 N
Puisano
Hoa tsebahala hore:
Boima ba ntho e moeeng (w) = 100 Newtons
Keketseho ea bophahamo ba mokelikeli = bophahamo ba ntho e qoelitsoeng ka har'a mokelikeli (V) = 1,5 m3
Matla a khoheli a metsi a itseng = 10 N/m3
O botsitse: Boima ba ntho e ka har'a mokelikeli
Karabo:
Foromo ea boima ba ntho e ka har'a mokelikeli:
Boima ba ntho e metsi = boima ba ntho e moeeng – boholo ba matla a ho phaphamala
Boima ba ntho ka hara metsi = 100 Newtons – boholo ba matla a ho phaphamala
Qala ka ho bala boholo ba matla a ho phaphamala e le hore o ka bala boima ba ntho e ka hara mokelikeli.
Foromo ea matla a ho thothomela:
FA = ρ g V
Lintlha :
FA = matla a ho phaphamala = matla a tswang mokelikeling nthong e leng mokelikeling
ρ = bongata ba mokelikeli
g = ho potlaka ka lebaka la matla a khoheli
V = bophahamo ba ntho e qoelitsoeng ka har'a metsi
Ho potlaka ho bakoang ke matla a khoheli (g) hoa tsebahala, bophahamo ba ntho e qoelitsoeng ka har'a mokelikeli boa tsebahala, empa boima ha bo so tsejoe. Ka hona, qala ka ho bala boima ba mokelikeli.
Matla a khoheli a itseng:
Matla a khoheli a metsi a itseng = 10 N/m3
w / V = 10 N/m3
mg / V = 10 N/m3
m (10) / V = 10 N/m3
m / V = 1 kg/m3
ρ = 1 lik'hilograma / limithara3
Kahoo boima ba mokelikeli ke 1 kg/m3
Matla a maholo a ho phaphamala :
FA = ρ g V = (1 lik'hilograma / limithara3)(10 m/s2)(1,5 m3) = 15 kg m/s2 = 15 Newton
Boima ba ntho e ka hara mokelikeli:
Boima ba ntho ka hara metsi = 100 Newtons – 15 Newtons
Boima ba ntho ka hara metsi = 85 Newtons
Karabo e nepahetseng ke C.
Mehlala ea lipotso mabapi le molao oa Archimedes
