Question

Помогите с задачей!!! Подушку массой 3 кг прижимают к дивану с силой 10 Н. Найти силу трения подушки о диван, если подушку потащит за собой пёс. Коэффициент трения подушки о диван 0,9.

Answer 1

Сила трения = коэффициент * силу реакции опоры
сила реакции опоры = силе тяжести =m*g
Fтяж= 0,9*(3*10+10) =36H 

Answer 2

Problem Analysis

We are given the mass of a pillow (3 kg) and the force applied to it (10 N) when it is pressed against a sofa. We need to find the frictional force between the pillow and the sofa, given that the coefficient of friction between them is 0.9.

Solution

To find the frictional force, we can use the formula:

Frictional force = coefficient of friction * normal force

The normal force is equal to the weight of the pillow, which can be calculated using the formula:

Weight = mass * gravitational acceleration

The gravitational acceleration is approximately 9.8 m/s^2.

Let's calculate the weight of the pillow first:

Weight = 3 kg * 9.8 m/s^2

Now, we can calculate the frictional force:

Frictional force = 0.9 * Weight

Substituting the value of the weight, we get:

Frictional force = 0.9 * (3 kg * 9.8 m/s^2)

Calculating the above expression will give us the frictional force.

Calculation

Let's calculate the frictional force:

Weight = 3 kg * 9.8 m/s^2 = 29.4 N

Frictional force = 0.9 * 29.4 N

Frictional force = 26.46 N

Therefore, the frictional force between the pillow and the sofa, when the pillow is being pulled by a dog, is 26.46 N.

Conclusion

The frictional force between the pillow and the sofa, when the pillow is being pulled by a dog, is 26.46 N.