# As a result of braking, the speed of the car in 3 seconds decreased from 72 km / h to 7.2 km / h

As a result of braking, the speed of the car in 3 seconds decreased from 72 km / h to 7.2 km / h. What is the braking force equal to? Vehicle weight 2500 kg.

Initial data: t (deceleration duration) = 3 s; V1 (speed before braking) = 72 km / h (20 m / s); V2 (speed after braking) = 7.2 km / h (2 m / s); m (vehicle weight) = 2500 kg.

1) Determine the acceleration of the car during braking: a = (V2 – V1) / t = (2 – 20) / 3 = -6 m / s2 (a <0, the car was moving slowly).

2) Let’s calculate the braking force: F = | m * a | = 2500 * 6 = 15000 N (15 kN).

Answer: The braking force on the vehicle was 15 kN.

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