What force acts on a vehicle travelling in a straight line?

Answer: B — Momentum

A Gravitational force pulls the vehicle towards the Earth, but it may not necessarily influence its motion in a straight line. C: Centrifugal force is a fictitious force that only appears to act on objects in circular motion. A vehicle traveling in a straight line would not experience centrifugal force. D: Frictional force would only act on the vehicle if it was moving along a surface. In a straight line, the vehicle may experience very little frictional force. The correct answer is B because momentum is the force that maintains the vehicle's motion in a straight line. It is a product of the vehicle's mass and its velocity. The other options do not accurately describe the force acting on a vehicle traveling in a straight line.