Answer to Question #293691 in Mechanics | Relativity for Samantha Moistner

Question

When a soccer ball is rolling along a Grassy feild it does not continue moving forward. What is acting upon it to change its state

Answer 1

Explanation & Answer

• The ball was moving so that its state was the motion and you observe it changes its state to stationary after moving for some distance.
• So there should be an external force acting on it to cause that change in state according to Newton's first law.
• The sole forces acting on it are the normal force from the ground, its own weight ($\small mg$ ) and the friction from the ground ($\small f$ ).
• The first two forces are normal to the ball's motion so they do not cause any effect on that ball's state.
• Therefore, it is the friction from the ground that opposes the ball's motion eventually leading it a to rest
• There is some resistance from the surrounding air as well which can be neglected though.