Norah tied a string around a tennis ball, and then she swung it in a circle in front of her to demonstrate a planet orbiting the Sun. She explained that her hand represented the Sun, the ball represented a planet, and the string kept the ball from leaving the "orbit" around her hand. Why doesn't the string work in the same way as gravity? (1 point) Responses There is no difference between the two systems. There is no difference between the two systems. The string only pulls one way; gravity pulls both ways. The string only pulls one way; gravity pulls both ways. The string holding the ball in orbit is a contact force; gravity is a noncontact force. The string holding the ball in orbit is a contact force; gravity is a noncontact force. The string keeps the distance between the bodies the same; gravity makes the distance vary.
1 answer
The correct response is: The string holding the ball in orbit is a contact force; gravity is a noncontact force.
This highlights the fundamental difference between the forces at play in Norah's demonstration and the gravitational force that governs planetary motion. The string requires physical contact to exert force, while gravity can act over a distance without contact.
