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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