A railway car of mass m1 travelling at a velocity of v1 collides with a second car of mass m2 travelling at v2 and the two join together. What is their final velocity?
Momentum is conserved in any collision, and for a single body is given by p = mv. The momentum before is m1v1+m2v2, and the momentum after is (m1 + m2)u where u is the final velocity, so the final velocity is (m1v + m2*v2)/(m1 + m2).
Related Physics A Level answers
All answers ▸What's the difference between inertial and gravitational mass?
Why does temperature effect the resistance of conductors?
Derive the escape velocity from the surface of a planet with radius, r, and mass, M.
A ball is rolled, travelling 10 m north in 5s, then 10 m east in 10s. What is the total distance and average speed of the ball? What is the total displacement and average velocity of the ball?