Answer:
Objects cannot accelerate, or decelerate, unless acted upon by an external force.
Step-by-step explanation:
Newton's second law states that objects that possess mass continue to be in a state of rest, or constant motion, unless they are acted upon an external force. This external force may cause a change in the object's direction, or velocity, or both. The force is directly proportional to the acceleration or deceleration caused, and inversely proportional to the mass of the object.
The law is explained by the equation below which states that the sum of all forces must be equal to the acceleration/deceleration experienced by the object multiplied by its mass.
Σf = m*a
Σf = sum of all forces (net force applied)
m = mass of the object
a = acceleration/deceleration