A force is required for the object ball to change its motion.
To elaborate, the change in an object ball's motion, whether it's starting to move, stopping, accelerating, decelerating, or changing direction, is directly caused by the application of a force. This force is a quantitative description of an interaction that alters the ball's momentum.
Here's a breakdown:
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Inertia: An object at rest tends to stay at rest, and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by a force. This is Newton's first law of motion.
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Force as the Agent of Change: A force overcomes the inertia of the object ball, causing a change in its velocity. Velocity is a vector quantity encompassing both speed and direction.
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Types of Motion Changes:
- Starting Motion: A stationary object ball requires a force to initiate movement.
- Stopping Motion: A moving object ball requires a force to stop it. This could be friction from the table, or a collision with another ball.
- Changing Speed: A force can either increase (acceleration) or decrease (deceleration) the object ball's speed.
- Changing Direction: A force acting at an angle to the object ball's current motion will cause it to change direction. This is typically seen in collisions.
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Examples:
- When a cue ball strikes the object ball, the force of the cue ball causes the object ball to move.
- Friction between the object ball and the table surface gradually slows it down, demonstrating a force stopping motion.
| Type of Motion Change | Required Force |
|---|---|
| Start Motion | Applied force sufficient to overcome static friction |
| Stop Motion | Opposing force (e.g., friction, impact) |
| Change Speed | Force acting in the direction of motion |
| Change Direction | Force acting at an angle to the motion |
In essence, the object ball's motion remains constant (either at rest or moving with constant velocity) unless a net external force acts upon it.
