If a rigid body of constant mass is observed accelerating, what must be happening? A force is being applied to the mass.
Newton's second law states that when a constant force is given to a big body, it will accelerate or change its velocity at a constant rate. In the simplest case, if a force is applied to an object at rest, the object will accelerate in that direction.
Newton's second law states that a force can alter a body's motion. A body's momentum changes in size and direction at the same rate as the force pushing on it.
Learn more about Newton’s law here:
https://brainly.com/question/15280051
#SPJ4