Determine what will be the kinetic energy of a bus weighing 12 tons, if its initial speed was 54 km / h

Determine what will be the kinetic energy of a bus weighing 12 tons, if its initial speed was 54 km / h, and then, when braking, the friction force did the work of 6 MJ, and the bus climbed the slope by 5 m.

m = 12 t = 12000 kg.

V0 = 54 km / h = 15 m / s.

Atr = 6 MJ = 6,000,000 J.

h = 5 m.

g = 9.8 m / s2.

Ek -?

The kinetic energy Ek is determined by the formula: Ek = m * V2 / 2.

According to the law of conservation of energy, the kinetic energy of the bus Ek0 is spent on overcoming the friction force Apt and increasing the potential energy ΔEp: Ek0 = Amp + Ek + En.

Ek = Ek0 – Atr + En.

Ek0 = m * V0 ^ 2/2.

Potential energy is determined by the formula: En = m * g * h.

Ek = m * V0 ^ 2/2 – Atr – m * g * h.

Ek = 12000 kg * (15 m / s) ^ 2/2 – 6,000,000 J – 12,000 kg * 9.8 m / s2 * 5 m = -5238,000 J – this cannot be.

We see that the initial kinetic energy is not enough to overcome the friction force. An error was made in the problem.