What is the pressure on the rails of a four-axle car with a mass of 60m, if the contact area of one wheel with the rail is 10 cm²?

m = 60 t = 60,000 kg.

g = 10 m / s2.

n = 4.

S1 = 10 cm2 = 0.001 m2.

P -?

Pressure P is the ratio of the force F to the area S on which this force acts: P = F / S.

The car acts on the rails by the force of its weight, the value of which is expressed by the formula: F = m * g, where m is the mass of the car, g is the acceleration of gravity.

Since the car has n = 4 wheels, the area of ​​contact of one wheel with the rails is S1, the weight of the car is distributed over the area S = n * S1.

We find the pressure of the car on the rails P by the formula: P = m * g / n * S1.

P = 60,000 kg * 10 m / s2 / 4 * 0.001 m2 = 150,000,000 Pa = 150 * 10 ^ 6 Pa = 150 MPa.

Answer: the pressure of the car on the rails is P = 150 MPa.