"An object that is at rest will stay at rest unless an external force acts upon it. An object that is in motion will not change its velocity unless an external force acts upon it."
Basically, this law implies that an object is unlikely to change its state of motion unless some force is put on the object.
This concept is seen during a shot during multiple occasions. First, a ball must be put into motion by a kicker. After the duration of the shot, it can be completed in one of three ways, all of which also change the state of motion:
1) The ball is stopped by a goalkeeper who acts as an "external force" acting upon the ball and
changing its motion.
2) The ball comes in contact with the back of a net terminating its motion. In this case, the net
acts as the "external force" responsible for the change of motion.
3) The ball comes to rest because of the Force of Friction acting on it. Friction is acting as the
"external force" that changes the motion of the ball bringing it to a stop.
This concept is seen during a shot during multiple occasions. First, a ball must be put into motion by a kicker. After the duration of the shot, it can be completed in one of three ways, all of which also change the state of motion:
1) The ball is stopped by a goalkeeper who acts as an "external force" acting upon the ball and
changing its motion.
2) The ball comes in contact with the back of a net terminating its motion. In this case, the net
acts as the "external force" responsible for the change of motion.
3) The ball comes to rest because of the Force of Friction acting on it. Friction is acting as the
"external force" that changes the motion of the ball bringing it to a stop.
Force Diagram
The ball will move in the positive X direction. This change in motion is because of the force that was applied to ball. Otherwise, the ball would not have changed its state of motion.
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To the left is a diagram depicting Newton's First Law of Motion at the moment a player is taking a shot. The four forces acting upon the soccer ball are:
1) Force of Friction in the negative X direction. This force resists the movement of the ball. 2) Normal Force in the positive Y direction. This force balances out the Force of Earth. 3) Force of Earth in the negative Y direction. This forces balances out the Normal Force. 4) Force Applied by the player in the positive X direction. This is the greatest force making it in the same direction as the net force. Consequently, this means that the ball will travel in accordance with the force that is applied for the shot. |
First Law for Goalkeepers
During a shot, it is up to the goalkeeper on the opposite team to make a save to prevent the other team from scoring. In order to do so, they must change the state of motion the ball is in. Below is an example of a goalkeeper who did just that.
Pay attention to the changes of motion in the video in two places:
1) When #14 on blue shot the ball.
2) When the goalkeeper changes the direction of the ball's movement.
Pay attention to the changes of motion in the video in two places:
1) When #14 on blue shot the ball.
2) When the goalkeeper changes the direction of the ball's movement.