Final answer:
The force responsible for the inward acceleration of a train rounding a curve is the centripetal force, provided in this context by the friction between the train wheels and the tracks. (option b)
Step-by-step explanation:
The force responsible for the train's inward acceleration while rounding a curve is the centripetal force. This force always acts perpendicular to the velocity of the object in circular motion, directing it towards the center of the circle or curve. In this case, the curve has a radius of 570.
The formula for centripetal force (Fc) is given by:
Fc = m×v²/ r
where:
Fc is the centripetal force,
m is the mass of the object,
v is the velocity of the object, and
r is the radius of the curve.
In this scenario, gravitational force (a), frictional force (c), and magnetic force (d) are not responsible for the train's inward acceleration during circular motion. Gravitational force acts vertically downward and is not relevant to the horizontal circular motion. Frictional force may play a role but is not the primary force responsible for maintaining the circular path. Magnetic force is also not typically involved in the curved motion of trains.
The correct force responsible for the train's inward acceleration on the curve with a radius of 570 is the centripetal force, as per the principles of circular motion.