Arailroad car containing an angry bull is standing onthe
tracks, but the brakes are not set. the bull, mass m,
initiallystanding at one end of the car charges(runs) to the other
end andcrashes into the wall. what is the final velocity of the
railroadcar if its mass is m and the bull runs at speed v? explain
youreasoning.

= - M / m v

Explanation:

We must define a system formed by the wagon and the torro, in this case the forces of the movement are internal, so the moment is preserved, write the moment in two moments

Initial. Before the bull's movement, in this case the two are still

             p₀ = 0

Final. The bull is moving

            = M v + m

             p₀ =

              0 = M v + m

We cleared the train speed

            = - M / m v

The negative sign indicates that the train moves in the opposite direction of the bull

dang that balls went far

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.