Final answer:
The cannonball moves after it leaves the cannon only due to its initial velocity and is not propelled by any additional force, with gravity being the only force acting on it vertically.Option B is the correct answer.
Step-by-step explanation:
The student asked whether a force keeps the cannonball moving after it leaves the cannon. The answer is No, Only Initial Velocity. After the cannonball has been fired from the cannon, and ignoring air resistance, no additional force acts on the cannonball in the horizontal direction. Its movement is due to the initial velocity imparted by the cannon. In terms of vertical motion, the only force acting on the cannonball is gravity, which affects its vertical acceleration.
It is essential to understand the concept of projectile motion for this question. Projectile motion describes the motion of an object that is thrown or projected into the air and is subject to gravity. In the ideal case, where air resistance is ignored, the only force acting on the projectile after being launched is gravity pulling it downward. Therefore, the vertical position changes with time due to the constant acceleration caused by gravity, while the horizontal position changes based on the initial velocity.
Lastly, the forces acting on a parachute illustrate this concept well: a parachute experiences gravitational force, and upon opening, air resistance, which illustrates how different forces can impact the motion of objects through the air.