>> 10 .

5.

 


42.

, , . , , , . , , .

1. , , . 90 /. 60 . , , 2,5 . μ1 = 0,5.

. , .

(. 5.5) m , , Fp1 = μ1N, Fp2 = μ2N.

, .

0 - mυ2/2 = -F1s1 - Fp2s2 = -(μ1s1 + μ2s2)N.

, N = mg.

N , mυ2/2 = (μ1s1 + μ2s2)mg.

2. , , 1 , , 60. . , 30 .

. (. 5.6). :

22/2 - 0 = + .                     (1)

, . : OY.

, .

OY = mgΔy, Δ = h1 - h2.

O2O1 O1O2 = lcosα0, h1 = l - O1O2 = l(1 - cosα0), O2 O2 = lcosα, h2 = l - O2 = l(1 - cosα).

h1 - h2 = l(cosα - cosα0).

= mgl(cosα - cosα0).

(1),

m22/2 = mgl(cosα - cosα0).

:

OY h1.

:

3. υ0 = 10 /. hm, , hmax/2. .

. : 0 - mυ20/2 = -mghmax. : hm = υ20/2g = 5 .

.

. mυ2/2 - 0 = mgh = mghmax/2. ( .) hmax

    ,

4. . h . . μ.

. , (. 5.7).

:

2/2 - 0 = + .

, .

, = mgl sina = mgh.

F = μN = μmgcosα.

= -μmg cosα.

= -μmgh cosα/sinα = -μmghctgα.

(1), mυ2/2 = mgh - μmghctgα = mgh(1 - μctgα).

1. 1 2 . .

2. 4 , , 1 . , .

3. 2 υ = 5 + 4t + 2t2 . , .

1. 1000 , 30 / ? 0,3.

2. l = 0,9 . . μ = 0,5. υ0 , ?

3. υ0 = 150 /, 1/3 υ0. 10 . μ = 0,1. s , 10 %?

4. m 3m . υ = 3 /. μ = 0,2. , 40 %?

5. 4,8 , , 0,2 , 60 40 /, . , , 12 . .

 

 

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