19-um trem 200 m de comprimento move-se com velocidade escalar constante de 72 km/h. calcule o tempo decorrido para esse trem passar completamente:
a)por uma pessoa parada à beira da ferrovia; b)por um túnel de 100 m de extensão.

grav forces affect all objects magnetic forces affect magnetic objects and electric currents

80cm/s.

24cm/s.

53.3cm/s.

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.