Explanation:
The Simple Pendulum. A simple pendulum is defined to have a point mass, also known as the pendulum bob, which is suspended from a string of length L with negligible mass ((Figure)). Here, the only forces acting on the bob are the force of gravity (i.e., the weight of the bob) and tension from the string.
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By definition, we have to:
 Newton's first law states that any object will remain in a state of rest or with a uniform rectilinear motion unless an external force acts on it.
 Therefore, according to the first law of Newton, if the object is already in motion and has no force acting on it then, it will remain with a uniform rectilinear motion.
 Answer:
 The object will remain with a uniform rectilinear movement when the external force does not act on it.
 
        
                    
             
        
        
        
A motorcycle speeding up on the highway because kinetic involve movement