Newton's First Law of Motion
Introduction
- Objective: Understand and describe Newton's First Law of Motion.
- Application: Apply the law to both moving and stationary objects.
Newton's Laws of Motion
- Concept: Describes effects of forces on object motion.
- Three Laws: This lecture focuses on the first law.
Newton's First Law of Motion
- Stationary Objects:
- If the resultant force is zero, the object remains stationary.
- Moving Objects:
- If the resultant force is zero, the object continues to move in the same direction at the same speed (constant velocity).
Examples
Stationary Object
- No Forces:
- Object remains stationary due to zero resultant force.
- Balanced Forces:
- Example: 50 Newton force to the right and 50 Newton force to the left.
- Forces are balanced, resultant force is zero, object remains stationary.
Moving Object
- No Forces:
- Object continues moving with the same velocity (speed and direction unchanged).
- Balanced Forces:
- Example: 50 Newton force to the right and 50 Newton force to the left.
- Resultant force is zero, object continues moving at the same velocity.
Key Point
- Velocity Change:
- An object's velocity changes only if a resultant force is acting on it.
Application: Car Example
- Constant Speed:
- Example: Car moving at 15 m/s.
- Driving force (engine) acts to the left.
- Equal resistive forces (friction with air and road) act to the right.
Resultant Force Effects
Stationary Object
- Applied Force:
- 50 Newton force to the right causes acceleration to the right.
- Key Concept: Resultant force changes object speed.
Moving Object
- Resultant Force:
- 50 Newton force to the left causes deceleration (slows down).
- Key Concept: Resultant force changes object speed and can change direction.
Direction Change
- Upward Force:
- Resultant force on the bottom causes upward acceleration.
Conclusion
- Study Resource: Questions on Newton's First Law available in the revision workbook linked in the lecture.
[Music] denotes transitions or non-verbal moments in the lecture presentation.