# A car with a mass of 20 tons moves at a speed of 1.5 m / s and meets a platform with a mass of 10 tons

**A car with a mass of 20 tons moves at a speed of 1.5 m / s and meets a platform with a mass of 10 tons standing in the way. After the coupler is triggered, they will move at a speed.**

The solution of the problem:

To solve this problem, we need to apply the Law of Conservation of Momentum (MMP), which looks like this:

m * v1 + m * v2 = m * v1 ‘+ m * v2’.

In our case, since one platform has no speed, therefore, they have no speed, which means they have no momentum. Also, after hitching, they move together, which means that the total mass after hitching will weigh M = (m1 + m2).

That is, the Formula will look like this: m * v1 = (m1 + m2) * v3 (v3 is the speed of the cars after coupling)

Now you can find the speed of the cars after coupling:

v3 = (m * v1) / (m1 + m2) = (20 * 1.5) / (20 + 10) = 1 (m / s).

Answer: 1 (m / s)