Multiple unit electric train has 800 tonnes mass, the resistance to motion is 100 newton's tonnes of the train if the electric motor can provide 200kn tractive force, how long will it take to accelerate the train to a speed of 90km/hr from rest

c.the charges if the proton and electron and gravity

the moon affects the earth gravitation ally, causing certain motions of that body and also producing tides in its ocean and atmosphere. the tidal wave in our atmosphere is, however, far too minute to be an effective cause in any known meteorological phenomenon.

explanation:

a and c

c is 100% but i am confused in a