WACE Binge - Biomechanics

When a tennis ball travels over the net with a flight path that sees the ball dip early and then bouncing with a low kick off the ground. Which type of spin has applied to the tennis ball?

• Top Spin

• Back Spin

• Side Spin

• Turbulent Spin

Keegan Palmer won the Men’s Park Skateboarding gold medal at the Tokyo Olympic Games. His success hinged on his ability to manage tricks repeatedly that involved spinning in the air. Which of the following remained constant throughout his spinning manoeuvres?

• radial speed

• angular velocity

• moment of inertia

• angular momentum

A tennis ball hitting a swinging tennis racquet at high velocity will alter the coefficient of restitution of the tennis ball. High velocities result in

• an increase in coefficient of restitution of the tennis ball

• a decrease in the coefficient of restitution of the tennis ball

• a perfectly elastic collision of the coefficient of restitution

• no change in the coefficient of restitution of the tennis ball

Identify the correct reason why a golf ball is made with dimples.

• The boundary layer separates later, causing a decrease in form drag.

• The boundary layer separates later, causing an increase in form drag.

• The boundary layer separates earlier, causing a decrease in form drag.

• The boundary layer separates earlier, causing an increase in form drag.

Which of the following changes to a rugby player’s body position will allow them to be in the most stable position when bracing for an opposing force?

• minimise their base of support so they can accelerate more quickly

• place the line of their centre of gravity towards the direction of the oncoming force

• position stance in the opposite direction to the oncoming force

• increase the height of their centre of gravity

The principle of Coefficient of Restitution is very important in sports such as Tennis and Baseball. Select the correct statement regarding this principle below:

• A high coefficient of restitution means a large amount of energy is transferred between colliding objects.

• A coefficient of restitution of 1 represents a perfectly inelastic collision. In reality, these collisions do not exist however, as a small amount of energy is always lost through sound and heat.

• Increased temperatures, combined with increased velocity will have the result of increasing the coefficient of restitution.

• A golf ball has a lower coefficient of restitution than a baseball.

A junior cricketer is consistently being caught in the slips when batting because she is not strong enough to sufficiently control her favourite bat. Her coach recommends that she select a different bat. Which of the following alternatives would allow her to swing with greatest control?

• a longer bat with the same mass

• a shorter bat with less mass

• a heavier bat with the same length

• a lighter bat with the same length

Imagine an ice skater is airborne and in a fast spin with her arms held tightly to her body. When she extends her arms, which one of the following statements is true?

• She decreases her moment of inertia.

• She increases her angular speed.

• Her moment of inertia remains constant.

• Her total angular momentum remains constant.

The coefficient of restitution (COR) of an object is influenced by:

• Height of colliding bodies, velocity of collision, temperature of colliding bodies

• Angle of colliding bodies, velocity of collision, materials of bodies

• mass of colliding bodies, temperature of bodies, size of colliding bodies

• Velocity of collision, temperature of colliding materials, equipment and surfaces

Which statement best describes the spin on the balls in the diagrams below?

• Ball A has side spin

• Ball B has top spin

• Ball C has back spin

• They all have no spine