Question

Поезд массой 150 т двигался со скоростью 72км/ч. При торможении до полной остановки поезд прошел 500м. Определить силу сопротивления движению?

Answer 1

A=Ep F*S=mv^2/2 F=mv^2/2*s F=150*1000*20^2/2*500=60000 (Ньютон)

Answer 2

Calculation of Resistance Force

To determine the resistance force acting on the train during braking, we can use the equation:

F = m * a

where: - F is the force acting on the train (resistance force), - m is the mass of the train, and - a is the acceleration of the train.

Given: - Mass of the train (m) = 150 tons = 150,000 kg - Initial velocity (v) = 72 km/h = 20 m/s - Final velocity (v') = 0 m/s - Distance traveled during braking (d) = 500 m

To calculate the acceleration (a), we can use the equation:

a = (v' - v) / t

where: - v' is the final velocity, - v is the initial velocity, and - t is the time taken to come to a stop.

Since the train comes to a complete stop, the time taken to stop can be calculated using the equation:

t = d / v

Substituting the given values:

t = 500 m / 20 m/s = 25 s

Now, substituting the values of v, v', and t into the acceleration equation:

a = (0 m/s - 20 m/s) / 25 s = -0.8 m/s^2

Finally, substituting the values of m and a into the force equation:

F = 150,000 kg * (-0.8 m/s^2) = -120,000 N

Therefore, the force of resistance acting on the train during braking is -120,000 N. The negative sign indicates that the force is acting in the opposite direction to the motion of the train.