Terminal velocity is a key concept in IB Physics, especially within mechanics, forces, and motion through fluids. It describes the final, constant speed that an object reaches when falling through a fluid such as air or water. This concept ties together ideas from Newton’s Laws, drag forces, free-body diagrams, and acceleration. Students who understand terminal velocity deeply find many exam problems easier to solve, a trend frequently emphasized in The Quest for a 7 in IB Physics (https://www.revisiondojo.com/blog/the-quest-for-a-7-in-ib-physics) .
What Terminal Velocity Means
Terminal velocity is the constant speed reached by an object when the downward gravitational force is balanced by the upward air resistance (drag).
At terminal velocity:
- Net force = 0
- Acceleration = 0
- Velocity = constant
This means the object is still moving, but it is no longer speeding up. Instead, it continues falling at a steady speed because the forces acting on it are in perfect equilibrium.
This connection between force balance and motion directly reflects Newton’s First and Second Laws. Understanding these relationships is crucial for exam performance and is supported through strategic advice found in How to Get a 7 in IB Physics (New Syllabus 2025 Onward) (https://www.revisiondojo.com/blog/how-to-get-a-7-in-ib-physics-new-syllabus-2025-onward) .
How Terminal Velocity Occurs
When an object begins to fall:
- It accelerates downward because gravity is the only significant force.
- Air resistance increases as the object speeds up.
- Eventually, air resistance grows large enough to match the weight.
- Once the forces balance, net force becomes zero, so acceleration stops.
- The object then falls at terminal velocity, a constant speed.
This process appears frequently in Paper 2 long-answer questions and data-analysis tasks. Understanding how drag depends on speed is particularly useful, especially when interpreting velocity–time and acceleration–time graphs.
What Factors Affect Terminal Velocity?
Many real-world factors influence terminal velocity, including:
- Mass
- Shape of the object
- Cross-sectional area
- Density of the fluid
- Surface texture
- Orientation while falling
For example:
- A skydiver in a spread-eagle position has a lower terminal velocity.
- A skydiver head-first reaches a higher terminal velocity.
- Objects with large surface area encounter greater drag and slow down faster.
Recognizing these variables builds strong intuition for motion questions, which helps students perform better on conceptual sections of exams.
Terminal Velocity in Graphs
Terminal velocity is easy to identify on motion graphs:
- Velocity–time graph: a horizontal line where velocity becomes constant.
- Acceleration–time graph: acceleration drops to zero.
- Force–time graph: drag and weight become equal.
These graph interpretations often appear in Paper 3, so familiarity with them boosts exam readiness. For additional exam preparation guidance, students often rely on efficient methods like those in How to Cram IB Physics in 1 Week (https://www.revisiondojo.com/blog/how-to-cram-ib-physics-new-syllabus-2025-onward-in-1-week-a-survival-guide) .
Terminal Velocity in the IB Physics IA
Terminal velocity lends itself well to experimental investigation. Common IA ideas include:
- Measuring falling coffee filters to determine drag forces
- Investigating how shape affects terminal velocity
- Exploring how fluid density impacts falling speed
- Modeling terminal velocity mathematically with sensors
These investigations provide excellent data for curve fitting, uncertainty analysis, and error evaluation. Many motion-based IA ideas like this appear in Top 10 Fresh IB Physics IA Ideas 2025 (https://www.revisiondojo.com/blog/top-10-fresh-ib-physics-ia-ideas-2025-how-revisiondojo-can-supercharge-your-ia) .
Common Misconceptions
Students often misunderstand terminal velocity because they:
- Think terminal velocity means the object stops moving
- Forget acceleration becomes zero
- Mix up constant speed with zero force
- Believe heavier objects always fall faster (not always true)
- Ignore how drag depends on velocity and shape
Clarifying these misconceptions strengthens your understanding of forces and motion, key topics for IB Physics success.
FAQ
Is terminal velocity the same for all objects?
No. It depends on mass, shape, area, and the fluid the object moves through.
Can terminal velocity be reached in a vacuum?
No. Without air resistance, there is no force to balance gravity.
Do objects always reach terminal velocity before hitting the ground?
Not always. Short drops may end before drag grows enough to balance weight.
RevisionDojo Call to Action
If you want deep understanding of motion, forces, and all major IB Physics topics, RevisionDojo provides the clarity, structure, and exam strategies you need. From IA design to efficient revision, RevisionDojo helps you achieve your best performance.
