A train weighing 400 tons moves at a speed of 40 km / h and stopped after braking.

A train weighing 400 tons moves at a speed of 40 km / h and stopped after braking. What is the braking force if the stopping distance is 0.4 km?

Initial data: m (train weight) = 400 t (in SI system m = 400 * 10 ^ 3 kg); V0 (speed before braking) = 40 km / h (in SI system V0 = 11.11 m / s); S (stopping distance) = 0.4 km (SI S = 400 m).

To calculate the required braking force, we will use Newton’s second law: F = m * a = m * V0 ^ 2 / 2S.

Let’s make a calculation: F = 400 * 10 ^ 3 * 11.11 ^ 2 / (2 * 400) = 61728.4 N ≈ 61.7 kN.

Answer: The required braking force was 61.7 kN.