The bus weighing 13 tons moves evenly at a speed of 36 km / h. The friction coefficient is 0.03.

| January 29, 2021 | education

The bus weighing 13 tons moves evenly at a speed of 36 km / h. The friction coefficient is 0.03. Determine the current in the motor winding if the voltage is 600 V and the motor efficiency is 70%.

m = 13 t = 13000 kg.

V = 36 km / h = 10 m / s.

μ = 0.03.

U = 600 V.

Efficiency = 70%.

g = 10 m / s2.

I -?

Let’s write down the formula for the engine efficiency: efficiency = Ap * 100% / Az.

Ap = F * S, where F is the thrust force of the engine, S is the movement of the bus.

Since the bus moves uniformly in a straight line, the engine thrust force F is balanced by the friction force Ftr: F = Ftr.

The friction force Ftr is determined by the formula: Ftr = μ * m * g.

Ap = μ * m * g * S.

Az = I * U * t.

Efficiency = μ * m * g * S * 100% / I * U * t = μ * m * g * V * 100% / I * U.

The current I will be determined by the formula: I = μ * m * g * V * 100% / efficiency * U.

I = 0.03 * 13000 kg * 10 m / s2 * 10 m / s * 100% / 70% * 600 V = 928.5 A.

Answer: the current in the motor winding is I = 92.85 A.



One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.