# The tram, which was traveling at a speed of 20 m / s, braked sharply. At what distance the tram

March 26, 2021 | education

| **The tram, which was traveling at a speed of 20 m / s, braked sharply. At what distance the tram will stop if the coefficient of friction is 0.3.**

When solving the presented problem, you should use the distance formula. Next, we transform it by substituting the formulas for the quantities – the formulas for speed and time:

s = ut = (u0 + u) / 2 * (u – u0) / a = u ^ 2 – u0 ^ 2 / 2a.

The final speed of the tram is zero:

u = 0

s = u0 ^ 2 / 2a. (one)

We see that only the acceleration value is missing to calculate the distance.

We calculate it through the force formula:

F = ma

Ftr = μmg

Substituting the formulas into each other, we get:

ma = μmg;

a = μg.

Let’s substitute it in formula 1:

s = u0 ^ 2 / 2μg = 20 ^ 2 / (2 * 0.3 * 9.8) ≈ 68 m.

Answer: 68 m.

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