Final answer:
The cylindrical disc accelerates in the direction of the constant force applied, owing to Newton's second law of motion. It doesn't speed up indefinitely because the acceleration produced by the constant force is also constant. The disc does not move in a curved path because there is no centripetal force guiding it.
Step-by-step explanation:
When a uniform cylindrical disc of radius 'r' and mass 'm' is pulled over a horizontal frictionless surface by a constant force, it accelerates in the direction of the pull. This is because there is no friction to slow it down or any forces that might cause it to move in a curved path. This represents one aspect of Newton's second law of motion, which states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.
It should be noted that the cylindrical disc does not speed up indefinitely because the force applied on it is constant. As a result, the acceleration — increase in velocity per time — is also constant. Therefore, the correct answer is C), the disc speeds up but not indefinitely.
Understanding uniform circular motion and the principles of centripetal force can help in comprehending why the disc does not make a curved path. In a system experiencing uniform circular motion, there is a centripetal force pulling the object towards the center, causing it to move in a circle. However, in this case, as there are no forces causing the disc to deviate from a straight line, it does not move in a curved path.
Learn more about Newton's second law of motion