# Determine at what speed a car with a mass of 1.5 tons was moving before the start of braking

August 28, 2021 | education

| **Determine at what speed a car with a mass of 1.5 tons was moving before the start of braking if, with a friction coefficient of 0.6, the braking distance is 60 m**

Data: m (vehicle weight) = 1.5 t (1500 kg); μ (coefficient of friction) = 0.6; S (braking distance) = 60 m.

Reference values: g (acceleration due to gravity) ≈ 10 m / s2.

1) Determine the acceleration of the vehicle during braking: m * a = Ftr. = μ * m * g, whence a = μ * g = 0.6 * 10 = 6 m / s2.

2) Let’s calculate the speed of the car before braking: S = V02 / 2a, whence V0 = √ (2a * S) = √ (2 * 6 * 60) = √720 = 26.83 m / s.

Answer: Before the start of braking, the car was moving at a speed of 26.83 m / s.

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