充.4
1. ................................................................................5
5
6
2. ......................................11
..11
..12
3. .................................................................20
..20
..22
4. ....................................................29
..29
..32
..38
. , , .
, . . . . , .
Δ t Δ r Δ t:
, .
Δ t S, , Δ t:
.
, :
.
-
; ,
.
:
,
,
υ 0 t = 0, a .
: .
: ,
:
,
R , .
:
.
:
φ,
ω = ,
ε= = .
:
ε t
φ = ω0 t + ε ,
ω0 t =0, e .
|
|
: υ = ω R, a τ = ε R.
1
S t S=A+Bt+Ct 2 +Dt 3, =0,14 , D =0,01 . 1 ? t = 0 t = 1 ?
t :
a = = (B+ 2 Ct+ 3 Dt 2 ) = 2 C+ 6 Dt.
t, a = 1 .
: t = .
, :
t = = 12 .
t 1 t 2, t 1 t 2 t 2 t 1:
a = .
:
υ = B+ 2 Ct+ 3 Dt 2,
υ 1 = B+ 2 Ct 1 + 3 Dt 12,
υ 2 = B+ 2 Ct 2 + 3 Dt 22.
:
υ 2 υ 1 = 2 (t 2 t 1)+ 3 D (t 22 t 12) = (t 2 t 1)[2 +3 D (t 2+ t 1)],
:
a = = 2 + 3 D (t 2+ t 1).
, :
a = 0,28 + 3.0,01 .1 = 0,31 .
2
υ 0 = 14,7 , α = 30 . t = 1,25 , . .
|
, υx υy. υ υ , a τ g ( a τ υ , υy g y). , an a τ, υx, υ, υ.
υx = υ 0 cos α = const,
υ = - υ 0 sin α + gt
( y ),
υ = .
:
= , = ,
a τ = g , an = g .
:
an = ,
R = = .
, :
aτ = = 3,55 ,
an = = 9,15 ,
R = = 10 .
3
, , 1 300 / 180 /. , .
: ω = ω0 ε t, φ = ω0 t ε .
ω, ν, ω = 2πν, φ = 2π Ν.
:
2πν = 2πν0 ε t.
|
|
ε = ,
2π Ν = 2π ν0 t ε = 2πν0 t 2π (ν0ν) = 2π (ν0+ν) ,
N = (ν0+ν) .
, :
ε = 750 -2 = 0,208 -2,
N = 240 .
4
, , 2 , , 60 .
|
, an = a τ tg α. (1)
an aτ :
an = ω2 R, a τ = ε R,
(1)
ω2 R = ε R tg α. (2)
ω = ε t.
(2):
ε2 t 2 = ε tg α,
ε = = 0,43 -2.
:
,
m , , .
: .
:
= .
F ds :
dA = Fs ds = Fds cosα,
α .
:
A = .
, : N = .
, , :
N = .
:
,
m , υ .
:
E = mgh
(m , g , h , );
:
E =
(k , x ).
:
Σ = const.
:
E = E k + E = const.
: A conp = E 1 E 2.
5
, , , 25% . ?
. , ( ), , F = μ Ν.
:
mg = N
F = T
mg = T m
: μ mg = mg,
μ =
6
x y :
: m = m +
x x x : m = m + +
:
ma=T mg (3)
:
ma = T + mg sina (4)
0 = N mg cos a (5)
(3) (4), :
2 ma = mg + mg sin a,
a = g
, , (3) ( (4)), : T = mg ma = mg
:
a = 9,8 = = 2,45
T = 1 ∙ 9,8 = 7,35 H
|
|
7
20 , , 6 . 54 /. : 1) ; 2) , .
:
A = 0 = ,
, , .
, :
A = F . S,
S = =
:
m = 2.104 , F = 6.103 , υ = 15 ,
:
A = = 2,25.106 = 2,25 ,
S = = 358 .
8
α= 60 υ 0=15 /. , : 1) ; 2) . m = 0,2 . .
, .
:
υx = υ 0cos a,(6)
υ υy = υ 0sin a gt (7)
a x t :
υ 2 = υ 02 cos2 a + (υ 0sin a gt)2= υ 02 2 υ 0 gt sin a + g 2 t 2.
t :
h = υ 0 sin a - . (8)
, t:
E k = = (υ 02 2 υ 0 gt sin a + g 2 t 2),
E = mgh = (2 υ 0 gt sin a g 2 t 2),
E = E k + E = .
υy = 0. = ( (7)), h max= ( (8)).
E k = = ,
E = mgh max = ,
E = E k+ E = .
. t = 1 c.
E k=17,4 , E = 5,1 , E = 22,5 .
:
E k =16,9 , E = 5,6 , E = 22,5 .
9
m 1 = 10 , m 2= 5 , . m 3= 100 , υ 0 = 500 /. υx , : 1) , 2) υ 1= 18/, , 3) υ 1= 18 /, , .
, - ( ) . . (m 1+ m 2+ m 3) υ 1, υx, (m 1+ m 2) υx, υ 0 + υ 1, m 3(υ 0+ υ 1). :
(m 1 + m 2 + m 3) υ 1 = (m 1 + m 2) υx + m 3(υ 0 + υ 1),
υx = = υ 1 υ 0.
, υ 1 υ 0:
1) υ 1 = 0
υx = 3,33 /.
, ;
2) υ 1 = 18 / = 5 /,
υx = 5 3,33 = 1,67 /.
, ;
3) υ 1 = 18 / = 5 /
|
|
υx = 5 3,33 = 8,33 /.
, , , .
10
, , , , . 1000 . 1 . , , 10.
.
,
, . mυ, . υ 1, (M + m) υ 1.
:
m υ = (M + m) υ 1,
υ 1 = υ.
:
E k = υ 12= υ 2= .
h, :
E k = E Þ = (M + m) gh. (9)
h
h = L L cos a = L (1 cos a).
(9), :
a L = gL (1 cos a),
h :
υ = .
, :
υ = 1001 543 /.
11
, , . , , 9,8 .
, .
L :
, . :
man = m = T 2 mg.
, . , :
mg + T 1 = T 2 mg,
T 2 T 1 = 2 mg,
m = .
: m = = 0,5 .
12
10 100 . ?
, ,
. .
, : = tg a.
an,
= tg a,
υ = =41,5 /.
:
I = Σ mi ∙ ri 2,
mi i , ri .
, :
I = m (R 12 + R 22).
I = mR 2.
I = mR 2.
I = mR 2.
I = ml 2.
, :
I = I 0 + ma 2,
I , I 0 , , , m , .
: I e = M,
I , , e , , .
F : M = F l,
l , , .
: L = I ω,
I , ω .
: L = m υ r,
m , υ , r , , .
: Σ Li = const.
:
E k = ,
I , ω .
:
E k = + ,
m , υ 0 , I 0 , , ω .
|
|
13
m R. .
dr.
dm = rp r 2 dr,
ρ , .
dI = dm.r 2.
:
I = = ρπ r 4 dr = ρ R 5.
:
m = = = R 3,
ρ = ,
I = = mR 2.
14
, 245 ∙2, 20 /. , , . : 1) ; 2) , .
. .
ω 0 = 2 π ν 0, ω = 0,
0 = 2 π ν 0 - ε t,
ε = .
M = I ε = .
:
φ = ω0 t - ,
φ =2π N, ω 0 = 2 π ν 0, ε = .
:
2π N = 2 π ν 0 t - = 2 π ν 0 t - = .
:
N = .
, :
M = = 506 ,
N = = 600 .
15
R = 20 , I = 0,1 ∙2, , m = 0,5 . h 1 = 1 . : 1) ; 2) ; 3) . .
|
. M = I ε,
, = TR, I ,ε = .
TR = I .
:
T = I (10)
:
mg = a (m + ) = am (1 + ).
:
a = . (11)
:
h 1 = ,
t = = .
:
υ = at = .
, :
E k = = .
(11) (10), : T = = .
, :
t = = 1,1 c,
E k = = 0,82 ,
T = = 4,1 .
16
m = 1 , , . υ = 10 /, 8 /. Q, .
:
E k = + . (12)
I = ,
w = .
(12):
E k = + = m υ 2.
, , :
Q = E k1 E k2 = m υ 12 - m υ 22 = m (υ 12 - υ 22).
, :
= ∙1(100∙10-4 64.10-4) = 10-4 = 2,25∙10-3 = 2,52 .
17
, υ = 9 /. m = 78 , m 1 = 3 . .
.
E k = + .
, , I = , w = .
: E k = + = .
/: υ = 2,5 /.
: E k =253 .
18
85 , . , ?
, .
,
2- 1= l . n = mgℓ ,
.
υ , ,
w = .
, , :
I = m l 2 = m = m l 2,
ml 2 , , .
:
E k = = . = .
, :
= mgl,
υ = .
: υ = 7 /.
19
m 1 = 60 m = 100 . , 5 ? 4 /. 10 . , .
,
. , . r, u = w r. ,
υ, υ w r, L 1 = m 1(υ w r) r. :
L = I w,
I .
, , :
I = mR 2.
:
O = L 1 + L = m 1(υ w r) r mR 2w,
:
w = .
:
n = 60 = .
:
n = = 0,49 /.