Question

Чему равен коэффициент трения между наклонной плоскостью и бруском, если при постепенном увеличении угла наклона наклонной плоскости брусок начинает скользить по ней тогда, когда угол наклона становится равным α ?

Answer 1

Так как в условии сказано что скольжение наступает при определенном угле
 то в момент начала движения mg+N+Fтр=0 ( векторно)

в проекциях 
ОX     m*g*sina - Fтр=0
ОY    m*g*cоsa=N
sina/cosa=tga=Fтр/N=k

Ответ k=tga

Answer 2

Coefficient of Friction between an Inclined Plane and a Block

The coefficient of friction between an inclined plane and a block determines the resistance to motion when the block starts to slide down the inclined plane. In this case, the angle of inclination at which the block starts to slide is denoted as α.

The coefficient of friction, denoted as μ, can be calculated using the formula:

μ = tan(α) Please note that the coefficient of friction is specific to the materials in contact and can vary depending on the surface conditions and other factors. The value of μ can range from 0 to 1, where 0 represents no friction and 1 represents maximum friction.

It is important to mention that the coefficient of friction is a dimensionless quantity and does not have any units.

I hope this answers your question! Let me know if you need further clarification.