A student performs an experiment in which a ball travels in a perfect circle. The ball is attached to a string and travels in the horizontal, circular path, as shown in Figure 1. At time to the ball has a speed vo. During the time interval of 0 s to 2 s, the force of tension in the string is recorded and graphed, as shown in Figure 2.
Is the system consisting of the ball, string, and student an open system or closed system, and why?
A
Open system, because a net centripetal force of tension is exerted on the ball that changes the direction of the ball.
B
Open system, because the force due to gravity from Earth is an external force that is exerted on the ball-string-student system
с
Closed system, because the force of tension remains constant and does not change the tangential speed of the ball as it travels in its circular
path
D
Closed system, because the ball travels in a closed circular path