does an object traveling at constant speed have no force?

Question

Newton's law says that force is the mass of an object times its acceleration. F = m.a
If a train is moving at a constant speed say 50mph from point A to point B, its acceleration will be zero because the speed is not changing. Does this mean that the train's force is zero?

Pls help

Answer 1

If the train is traveling at a constant speed, then there is no NET force acting on the train. However, even though the net force is equal to zero, there can and will be many individual forces acting on the train. Gravity acts downwards but the tracks exert an upwards normal force. A drag force (air resistance) resists the train's forward motion, as does friction between the tracks and the wheels. At the same time, the wheels are driven by forces generated electrically or through a furnace.

Answer 2

The force experienced by the train (and its passengers and contents) will be zero in the direction in which it is heading. There is still force downwards from gravity.

If you were in a spaceship, travelling in a straight line at constant velocity then you would experience no acceleration and therefore we "weightless".

Answer 3

The answer depends on the assumptions. If the train has frictionless wheels, no aerodynamic drag and is considered ideal, then no force is needed at constant speed.

However, real trains have aerodynamic drag and friction so they require a force even at constant speed.

Answer 4

That is correct. However, it has massive amounts of momentum.