To calculate force of sliding friction (Ftr), you need to know the time braking and stopping distance.
If you know the time braking , but not known for its stopping distances, you can perform a calculation using the formula: s = υ0⋅t / 2, where s - the length of braking distance, t - time braking , υ0 - the speed of the body at the start of braking .To calculate the speed of the body at the start of braking you need to know the amount of braking distance and time braking .Calculate it using the formula: υ0 = 2s / t, where υ0 - the speed of the body at the start of braking , s - the length of the braking distance, t - time braking .
Please note that the braking distance is proportional to the square of the initial speed before braki
ng and inversely proportional to the force of sliding friction (braking force ).That is why, for example, on a dry road (in the calculations for cars) the braking distance is shorter than slippery.
Once you become aware of all the values, substitute them into the formula: Ftr = 2m⋅s / t2, where Ftr - sliding frictional force (braking force ), m - mass of the moving body,s - the value of the braking distance, t - time braking .
Knowing braking force , but without knowing its time, you can make the necessary calculations by the formula: t = m⋅υ0 / Ftr where t - time braking , m - massmoving body, υ0 - the speed of the body at the start of braking , Ftr - braking force .
Calculate force of sliding friction by another formula: = μ⋅ Fnorm Ftr where Ftr - sliding frictional force (braking force ), μ - friction coefficient Fnorm - the force of normal pressure, pressingbody to a support (or mg).
Determine friction experiments.In textbooks on physics it is usually already indicated in a task, unless you want to calculate it for a particular body during laboratory work.To do this, place the body on an inclined plane.Determine the angle of inclination at which the body begins to move and learn at their own tables or calculate the tangent of the angle obtained α (the ratio of the opposite leg to an adjacent).This will be the value of the coefficient of friction (μ = tg α).
- find friction torque