Question

A yellow train of mass 100 kg is moving at 8 m/s toward an orange train of mass 200 kg traveling in the opposite direction on the same trac at a speed of 1 m/s. They collide and stick together! What is the velocity of
the new combined train?
A. 8 m/s
B. 2 m/s
C. 4 m/s
D. 10 m/s

Answer 1

Answer:

B. 2 m/s

Explanation:

With all collisions, momentum is conserved. This is known as the Conservation of Momentum.

To find the momentum of an object, multiply its mass by its velocity.

$m_yv_y+m_ov_o=(m_y+m_o)v_f$, solving for vf

Plugging in numbers, we get:

$100\cdot 8 + 200(-1)=(100+200)v_f$

$300v_f=600,\\v_f=\boxed{2\text{ m/s}}$