Amoving freight car collides with an identical one that is at rest. if momentum is conserved, what happens to the second car after the collision? it attains the same speed as the first car. it moves at half the speed of the first car. it moves at twice the speed of the first car.

For all elastic collisions we have

also by momentum conservation we will have

since two cars are identical so we know that

now by solving two equations we will have

so the correct answer must be

It attains the same speed as the first car.

atomic = no of protons.

mass number-atomic number = neutron number

it would be kevlar ^^