Sebastián se encuentra en una parada de trenes. El tren n° 15 pasa sin detenerse a una velocidad de 35 km/h. Si situamos el sistema de referencia en Sebastián, ¿el tren n° 15 está en reposo o en movimiento?

the train is moving relative to the boy

Explanation:

When the train is on the road, it moves with respect to the Earth at a speed of 35 km / h. When we arrive at the station we change the reference system from the ground to the boy who is in the station, therefore the speed of the train can change

               v ’= v + u

where v is the speed of the train with respect to the boy, v is the speed with respect to the ground and u the speed of the boy with respect to the ground

In general, the people in the station are still, that is, their speed with respect to the ground is zero, consequently the speed of the train does not change.

The correct answer is that the train is moving relative to the boy.

note: the given question is incomplete.

complete question is given below.

which is an example of kinetic energy?

a. the energy stored in ethanol  

b. a hockey puck sliding across the ice  

c. a compressed spring  

d. a ball sitting at the top of a ramp

solution: the kinetic energy is the energy posses by the virtue of the motion of the object.

in the given options, a, c and d are the example of potential energy because it is the energy posses by the virtue of the rest of the object. but option b has the kinetic energy as the object is in motion.

hence, a hockey puck sliding across the ice   is the apex example of kinetic energy.

so, the option (b) a hockey puck sliding across the ice   is the correct option.