Брусок масою 2 кг рівномірно тягнуть по столу за до горизонтальної пружини жорсткістю 50 Н/м. Чому дорівнює видовження пружини, якщо коефіцієнт тертя між бруском і столом становить 0, 25.​

Відповідь:10 см
Розв’язання:
Знайти х;
Fпружності=Fтетртя
k*x=u*m*g;візьмемо u коефіціент тертя.Будемо вважати g=10Н/кг;
x=u*m*g/k
x=0,25*2*10/50=0,1 м=10см

Rome is not only an ancient city or a capital of Italy. It is a special place where everyone can feel himself at home. You will never be alone in Rome, because it seems that all people know each other and even tourists don’t feel uncomfortable there.

Rome is obviously an amazing city where you can see and visit such famous monuments as the Colosseum, the Roman Forum, the Pantheon, the Trevi Fountain and Vatican City. All these and many other tourist attractions amaze and make such a great impression that you will never be able to forget them.

Apart from sightseeing, you can also explore Italian culture in Rome. You can feel yourself a part of a mysterious rite entering any patisserie or bar in the morning. Once you share your breakfast consisting of a cup of creamy cappuccino and filled croissant with those Italians who come to that place, you will become more relaxed and even “Italian”.

And finally, you can enjoy yourself in a big park area in Rome. It is called “Villa Borghese” and it is a perfect place to spend a hot and sunny day under its trees or to walk its wide paths in. In addition, Villa Borghese can offer you different other activities. You can visit famous “Borghese Gallery” and also a zoo placed in the park.

Consequently, Rome is a city where everyone can find his place. You can walk, visit museums, do shopping, go to opera and do many other things there. But there’s one thing that you will certainly do in Rome – you will enjoy yourself.

Объяснение:

Дано:

V₁ = 28 км/ч

V₂ = 26 км/ч

R = 30 м = 0,03 км

Пусть путь, который пробежит второй спортсмен до встречи = 2*π*R*k (k - коэффициент).

Так как они бегут по окружности, и первый спортсмен двигается быстрее, то на тот момент, когда первый догонит второго, первый пройдёт 2*π*R*(k + 1). Время пути одинаковое, тогда:

2*π*R*(k + 1) / V₁  =  2*π*R*k / V₂

(2*π*R*k + 2*π*R)*V₂ = 2*π*R*k*V₁

2*π*R*(k*V₂ + V₂ - k*V₁) = 0

k*(V₂ - V₁) = - V₂

k = - V₂ / (V₂ - V₁)

k = - 26 / (26 - 28) = 13.

Время встречи от начала забега произойдёт:

t = 2*π*R*k / V₂ ;

t = 2*π*0,03*13 / 26 = 0,0924 ч ≈ 339 c

ответ: 339 с.