Characteristics of Motion
What are the three characteristics of motion?
Linear, angular, and general motion.
Define the "Base of Support" and give one sporting example of a wide base.
The area beneath an object in contact with the ground. Example: Spreading feet wide in a tennis "ready position."
Define "Force Summation".
Force summation is the process of adding together the forces produced by different body parts to create maximum velocity.
List the three main factors that affect how far a projectile (like a shot put) will travel.
Height of release, Angle of release, and Speed of release.
Define Newton’s First Law (Inertia) in your own words.
An object will stay still (or keep moving) unless a force (like a kick or friction) acts on it.
What is the difference between "Linear Motion" and "Angular Motion"?
Linear is motion is motion in one direction (straight or curved). Angular is motion around an axis (rotation).
Where is the "Center of Gravity" usually located on a human standing in a neutral position?
Generally in the pelvic/hip region (around the belly button).
In a sequential movement like a shot put or a tennis serve, which muscle groups must start the movement, and which should finish it?
You must start with the largest, heaviest muscle groups (legs/glutes) and finish with the smallest, fastest muscle groups (wrists/fingers).
What is the name of the curved, symmetrical path that a ball follows through the air, and what is the main force that pulls it back to Earth?
Trajectory and gravity.
Provide the formula for Newton’s Second Law.
Force = Mass x Acceleration (F=ma).
Define "General Motion" and give an example from a common sport.
A combination of linear and angular motion. Example: A rugby player running (linear) while their legs rotate at the hips (angular).
Explain the relationship between the height of the Center of Gravity and a rugby player’s ability to stay upright in a tackle.
Lowering the COG (bending knees) increases stability because it brings the mass closer to the ground, making it harder for an external force to pull the Line of Gravity outside the Base of Support.
Evaluate why an elite athlete uses their whole body for a skill that could be done with just the arms (like a dart throw vs. a javelin throw).
Using the full Kinetic Chain involves more total body mass, which generates greater force (F=ma).
What is the theoretical optimal angle of release for the greatest trajectory of a projectile?
45°
Explain why it requires more force to accelerate a shot put than a tennis ball to the same speed.
Because the shot put has more Mass, it requires a much larger Force to achieve the same Acceleration as the lighter tennis ball (F = ma).
Explain how a gymnast uses angular motion at the hip to create linear motion in a forward roll across the floor.
By rotating the hips (angular), the gymnast's center of mass is pushed forward in a straight line (linear) across the mat.
Use the term "Line of Gravity" to explain why a sprinter leans forward when starting a race.
By leaning forward, the LOG moves to the very front edge of the BOS. This makes the athlete "unstable" in a forward direction, allowing gravity to help them accelerate faster.
Explain why a "pause" in the middle of a basketball shot reduces the total force applied to the ball.
A pause breaks the momentum transfer. For maximum force, each body part must reach its peak speed just before the next part begins; a pause means the force from the legs is lost before it can be "passed" to the arms.
Why are the most important principles of projectile motion different for a basketball player shooting a half-court buzzer beater vs a free throw?
A half-court shot prioritises speed of release and a lower angle (near 45°) to maximise horizontal distance and reach the hoop. In contrast, a free throw focuses on a higher angle of release (50°–55°) to create a steeper entry arc, which effectively makes the hoop "wider" and improves accuracy.
Using Newton's Third Law (Action/Reaction), explain how a swimmer moves forward through the water.
The swimmer pushes back against the water (Action), and the water pushes the swimmer forward with equal force (Reaction).
Explain how a cyclist uses angular motion at the hip to create linear motion of the body/bicycle. What type of motion is this altogether?
By rotating the hips (angular), the cyclist's center of mass is pushed forward in a straight line (linear)with the bike. This is called general motion.
Evaluate the trade-off between high stability and agility. Why might a tennis player intentionally narrow their base of support just before a sprint?
While high stability (wide/low) prevents falling, it creates high inertia, making it harder to change direction. A tennis player narrows their base slightly to "unlock" their stability, allowing for a faster "re-entry" into motion (agility).
Explain how a deeper "wind-up" or a longer "follow-through" affects the final speed of a projectile.
A larger Range of Motion increases the distance and time over which force is applied. This allows the body more "room" to accelerate each part to a higher velocity before the point of release.
Evaluate why an elite javelin thrower might release their javelin at 35° instead of the theoretical "perfect" 45°. Justify your answer using the concept of Air Resistance.
At 45°, the javelin spends more time in the air, but it also faces more Air Resistance (drag) and wind. By releasing at a lower angle (35°), the athlete maximises Speed of Release and minimises the time air resistance can act on the javelin, leading to a more efficient flight path and a longer distance.
Justify the use of starting blocks in a race by applying Newton’s Third Law.
Blocks allow the sprinter to push horizontally. According to the 3rd Law, the blocks push back with equal force. Because the blocks are unmoving, 100% of that reaction force is transferred into the runner’s acceleration, optimising the start.