SCSA Physical Education Studies Biomechanics

Incorrect. Angular momentum is the rotational equivalent of linear momentum, describing an object's tendency to continue rotating, rather than the principle of total momentum remaining constant.

Incorrect. While momentum is transferred between objects during a collision, the term transfer of momentum does not describe the overarching law that the total momentum of the entire system remains unchanged.

Incorrect. Summation of momentum refers to the sequential coordination of body parts to generate maximum velocity or force, not the behavior of momentum during collisions.

Radial speed is not a conserved quantity and changes as the skater moves their limbs relative to their center of mass.

Angular velocity changes as the skater alters their body position (moment of inertia) to spin faster or slower.

The moment of inertia changes as the skater tucks or extends their body during the trick.

While leaning forward may slightly lower the center of gravity, the primary goal is to facilitate rapid forward acceleration, not just to lower the center of gravity.

Leaning forward does not increase the size of the base of support, which is determined by the placement of the sprinter's hands and feet on the ground.

Sprinters actually want to decrease their forward stability, not increase it, so they can quickly propel themselves forward at the start of the race.

Top spin creates a downward aerodynamic force (the Magnus effect) that causes the ball to drop quickly, rather than staying in the air and dropping slowly.

A shot that stays low and flat is characteristic of a drive with little to no spin, whereas top spin is used specifically to allow a higher, safer clearance over the net.

Top spin causes the ball to dip sharply rather than drop slowly, and it is typically hit with a higher arc rather than flat over the net.

This describes a perfectly elastic collision where the coefficient of restitution is exactly $1$. In reality, a bouncing ball loses kinetic energy to heat and sound, so the velocities are not the same.

This implies a coefficient of restitution greater than $1$, meaning the ball gained kinetic energy during the bounce. This violates the law of conservation of energy.

Velocity is the defining factor of this concept. The coefficient of restitution is mathematically defined as the ratio of relative velocity after the collision to the relative velocity before the collision.

While increasing the distance increases torque, applying less force will decrease it. To produce the greatest torque according to $\tau = F \times r$, both force and distance must be maximized.

Torque is calculated as $\tau = F \times r$. Decreasing both the applied force and the perpendicular distance will result in the smallest amount of torque, not the greatest.

Although applying more force increases torque, decreasing the perpendicular distance reduces it. Both variables must be increased to maximize the total torque.

Kicking a football and shooting a basketball free throw both rely on the sequential summation of forces, where body parts move in a specific sequence to generate velocity at the end of the kinetic chain.

Throwing a dart and hitting a tennis forehand involve moving body parts in a sequence to transfer momentum to the projectile or racket, making them examples of sequential summation of forces.

Throwing a javelin and putting a golf ball both utilize sequential summation of forces to smoothly transfer energy from the larger, slower body parts to the smaller, faster ones.

Incorrect. Being streamlined minimizes the swimmer's frontal area, which is a primary and highly effective strategy for reducing form drag in the water.

Incorrect. Wearing a swim cap smooths the surface of the head and covers hair, effectively reducing skin friction drag.

Incorrect. Keeping the head aligned with the body helps maintain a horizontal, streamlined position, which minimizes form drag.

Incorrect. A basketball actually has significantly less mass than a medicine ball. According to Newton's second law ($a = F/m$), a greater mass would result in less acceleration, not more.

Incorrect. Inertia is directly related to mass, and a medicine ball has a greater mass (and therefore greater inertia) than a basketball.

Incorrect. Because the medicine ball has more mass, the same force will give it a smaller acceleration and thus a smaller initial velocity compared to the basketball.

This arrangement describes a first-class lever, where the axis (fulcrum) is located between the resistance (load) and the force (effort).

This arrangement describes a second-class lever, where the resistance (load) is located between the axis (fulcrum) and the applied force (effort).

Similar to option A, this describes a first-class lever with the axis (fulcrum) positioned between the force and the resistance.

Standing up tall raises the student's centre of gravity, which decreases stability and makes them easier to knock over.

Moving the feet closer together creates a narrower base of support, which significantly reduces balance and stability during a tackle.

While lowering the centre of gravity is beneficial, moving the line of gravity away from the tackle (leaning backward) makes the student much more likely to fall backward upon impact.

Padding actually extends the duration of the impact. Decreasing the time of the collision would result in a larger force and a higher chance of injury.

While the average force is ultimately decreased, the padding does not do this directly; it achieves this reduction in force specifically by extending the time of the impact.

Increasing the force applied to the hand would increase the chance of injury, which is the exact opposite of the padding's purpose.

This is incorrect because moving the fulcrum closer to the resistance increases the mechanical advantage, which actually decreases the amount of effort force needed.

This would only be true if the fulcrum were placed exactly in the middle, making the effort arm and resistance arm equal in length.

This is incorrect because a lever cannot eliminate the need for force entirely; it only reduces the amount of effort force required by increasing the distance over which it is applied.