Odpowiedzi

Najlepsza Odpowiedź!
2009-12-26T22:17:51+01:00
1.
m = 5 kg
a = 4 m/s^2
μ = 0,5

Fw = m • a
Fw = F - T
F = Fw + T
T = μ • m • g
F = m • a + μ • m • g
F = m • (a + μ • g)

F = 5 • (4 + 0,5 • 10) = 45 N

2.
m = 2 kg
α = 45*
F = 30 N
Fw = m • a
Fw = Fs + T
a = Fw / m
a = (Fs + T) / m
Fs = sin α • m • g
T = μ • cos α • m • g
a = g • (sin α + μ • cos α)

a = 10 • (sin 45* + 0,2 • cos 45*) = 8,5 m/s^2

3.
m1 = 2 kg
m2 = 3 kg
F = 50 N
f = 0,2

a) (do ciała m1)
a = Fw / m
m = m1 + m2
Fw = F - T
T = T1 + T2
T1 + T2 = f • m1 • g + f • m2 • g = f • g • (m1 + m2)
Fw = F - f • g • (m1 + m2)
a = [F - f • g • (m1 + m2)] / (m1 + m2)
Fn = m1 • {[F - f • g • (m1 + m2)] / (m1 + m2)}
Fn = 2 • {[50 - 0,2 • 10 • (2 + 3)] / (2 + 3)}
Fn = 16 N

b) (do ciała m2)
Fn = m2 • {[F - f • g • (m1 + m2)] / (m1 + m2)}
Fn = 3 • {[50 - 0,2 • 10 • (2 + 3)] / (2 + 3)}
Fn = 24 N

4.
m = 4 kg
F = 20 N
a = 3 m/s^2
f = ?
Fw = m • a
Fw = F - T
T = f • m • g
Fw = F - f • m • g
m • a = F - f • m • g
f = (F - m • a) / (m • g)
f = (20 - 4 • 3) / (4 • 10)
f = 0,2

5.
m1 = 1 kg
m2 = 2 kg
f = 0,3

a) (zwisa ciało m1)
a = Fw / m
a = (m1 • g - f • m2 • g) / (m1 + m2)
Fn = m1 • g - m1 • {[g • (m1 - f • m2)] / (m1 + m2)}
Fn = 1 • 10 - 1 • {[10 • (1 - 0,3 • 2)] / (1 + 2)}
Fn = 8,67 N

b) (zwisa ciało m2)
Fn = m2 • g - m2 • {[g • (m2 - f • m1)] / (m1 + m2)}
Fn = 2 • 10 - 2 • {[10 • (2 - 0,3 • 1)] / (1 + 2)}
Fn = 8,67 N
2009-12-26T23:23:07+01:00
1.
m = 5 kg
a = 4 m/s^2
μ = 0,5
Fw = m * a
Fw = F - T
F = Fw + T
T = μ * m * g
F = m * a + μ * m * g
F = m * (a + μ * g)
F = 5 (4 + 0,5 * 10) = 45 N

2.
m = 2 kg
α = 45*
F = 30 N
Fw = m * a
Fw = Fs + T
a = Fw / m
a = (Fs + T) / m
Fs = sin αmg
T = μ * cos α m g
a = g * (sin α + μ * cos α)

a = 10 * (sin 45* + 0,2 * cos 45*) = 8,5 m/s^2

3.
m1 = 2 kg
m2 = 3 kg
F = 50 N
f = 0,2

a) (do ciała m1)
a = Fw / m
m = m1 + m2
Fw = F - T
T = T1 + T2
T1 + T2 = f * m1 *g + f * g = f * g *(m1 + m2)
Fw = F - f * g *(m1 + m2)
a = [F - f *g *(m1 + m2)] / (m1 + m2)
Fn = m1 * {[F - f * g * (m1 + m2)] / (m1 + m2)}
Fn = 2 *{[50 - 0,2 *10 * (2 + 3)] / (2 + 3)}
Fn = 16 N

b) (do ciała m2)
Fn = 3 * {[50 - 0,2 *10 *(2 + 3)] / (2 + 3)}
Fn = 24 N

4.
m = 4 kg
F = 20 N
a = 3 m/s^2
f = ?
Fw = m *a
Fw = F - T
T = f *m *g
Fw = F - f *m *g
m *a = F - f *m *g
f = (F - m *a) / (m *g)
f = (20 - 4 *3) / (4 *10)
f = 0,2

5.
m1=1 kg
m2=2 kg
f = 0,3
a) (zwisa ciało m1)
a = Fw / m
a = (m1 * g - f *m2 *g) / (m1 + m2)
Fn = m1 *g - m1 *{[g *(m1 - f *m2)] / (m1 + m2)}
Fn = 1 *10 - 1 *{[10 *(1 - 0,3 *2)] / (1 + 2)}
Fn = 8,67 N
b) (zwisa ciało m2)
Fn = m2 *g - m2 *{[g *(m2 - f *m1)] / (m1 + m2)}
Fn = 2 *10 - 2 *{[10 *(2 - 0,3 *1)] / (1 + 2)}
Fn = 8,67 N

coś w 5 mi się lekko nie zgadzało, miałam wątpliwości, ale teraz widzę , że chyba jest ok, bo mój poprzednik też tak miał . Pozdro. ;)