Newton’s First Law in Sport
Newton’s First Law of Motion explains how objects behave when forces acting on them are balanced or unbalanced. In IB Sports, Exercise and Health Science (SEHS), this law is essential for understanding why athletes remain stationary, keep moving, or require force to change motion. It introduces the concept of inertia and provides a foundation for analysing movement in sport.
Newton’s First Law states that an object will remain at rest or continue moving at a constant velocity unless acted upon by an unbalanced external force.
Understanding Inertia
Inertia is the resistance of an object to changes in its state of motion. In sport, inertia explains why:
- A stationary object does not move without applied force
- A moving object does not stop or change direction without force
The greater the mass of an object or body, the greater its inertia. This means more force is required to start, stop, or change the motion of heavier athletes or objects.
In IB SEHS exams, inertia should always be linked to mass and resistance to change in motion.
Balanced Forces and No Change in Motion
When forces acting on an object are balanced, there is no change in motion.
This means:
- A stationary object remains stationary
- A moving object continues at the same speed and direction
For example, a hockey puck sliding across ice will continue moving until friction or another force acts on it. In sport, balanced forces explain why athletes maintain constant speed when no additional force is applied.
Unbalanced Forces and Change in Motion
Unbalanced forces cause a change in motion. This change may involve:
- Starting movement
- Stopping movement
- Changing speed
- Changing direction
In sprinting, an athlete applies force against the ground to overcome inertia and accelerate forward. This applied force is unbalanced, resulting in a change in velocity.
Sporting Examples of Newton’s First Law
Newton’s First Law can be applied to many sporting situations:
- A football remains stationary until kicked
- A cyclist continues moving until braking forces act
- A runner must apply force to stop suddenly
Using clear sporting examples strengthens IB exam answers and demonstrates applied understanding.
Importance for IB SEHS Exams
Newton’s First Law is often tested through application rather than definition. High-mark answers clearly explain inertia, identify balanced or unbalanced forces, and link these ideas to changes in motion during sport.
Avoid simply stating the law without explanation or application.
RevisionDojo Call to Action
If Newton’s laws feel abstract or difficult to apply in exam answers, RevisionDojo helps IB SEHS students master forces and motion with clear explanations and exam-style practice. It is the most effective way to turn physics concepts into exam marks.
Frequently Asked Questions (FAQs)
What is inertia in IB SEHS?
Inertia is the resistance of an object or body to changes in its state of motion and is related to mass.
When do forces not change motion?
When forces are balanced, there is no change in speed or direction.
How is Newton’s First Law tested in IB SEHS exams?
Students are often asked to apply the law to sporting situations involving starting, stopping, or maintaining movement.
