Question

две железнодорожные платформы движутся навстречу друг другу со скоростями 1,2 км/ч и 1,8км/ч. Масса первой платформы 16т,масса второй платформы 24 т. С какой скоростью и в каком направлении будут двигаться платформы после их соединения?

Answer 1

По закону сохранения импульса
m2*V2  - m1*V1 == (m1 +m2)* V
V= (m2*V2 -  m1*V1 )/ (m1+m2)  =(24*1,8  -  16*1,2)/40=24/40 =0,6 км/ч - скорость совместного движения( направлена в сторону платформы большей массы)

Answer 2

Problem Analysis

Two railway platforms are moving towards each other with speeds of 1.2 km/h and 1.8 km/h. The mass of the first platform is 16 tons, and the mass of the second platform is 24 tons. We need to determine the speed and direction of the platforms after they are connected.

Solution

To solve this problem, we can use the principle of conservation of momentum. According to this principle, the total momentum before the collision is equal to the total momentum after the collision.

The momentum of an object is given by the product of its mass and velocity. Therefore, the momentum of the first platform before the collision is equal to the product of its mass (16 tons) and velocity (1.2 km/h), and the momentum of the second platform before the collision is equal to the product of its mass (24 tons) and velocity (1.8 km/h).

After the platforms are connected, they will move together as a single object. Let's assume the final velocity of the connected platforms is v km/h.

According to the conservation of momentum, the total momentum before the collision is equal to the total momentum after the collision. Therefore, we can write the following equation:

(16 tons * 1.2 km/h) + (24 tons * 1.8 km/h) = (40 tons * v km/h)

Now, let's solve this equation to find the value of v.

Calculation

(16 tons * 1.2 km/h) + (24 tons * 1.8 km/h) = (40 tons * v km/h)

19.2 tons * km/h + 43.2 tons * km/h = 40 tons * v km/h

62.4 tons * km/h = 40 tons * v km/h

Dividing both sides of the equation by 40 tons, we get:

1.56 km/h = v

Therefore, the platforms will move together with a speed of 1.56 km/h after they are connected.

Conclusion

After the two railway platforms are connected, they will move together with a speed of 1.56 km/h.