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HMS, BM EQ-Bank 971

Explain the techniques swimmers can use to minimise drag and maximise lift forces during competition.   (5 marks)

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Sample Answer

  • Swimmers maintain head-spine alignment with horizontal body position to reduce form drag. This works because streamlined positioning allows water to flow smoothly around body contours, which prevents turbulence formation. As a result, resistance decreases by up to 40% compared to poor alignment.
  • Core muscle engagement keeps hips elevated at the water surface. This technique prevents legs from sinking below the body line, thereby reducing frontal surface area exposed to water. Consequently, form drag decreases significantly while buoyancy enables more efficient stroke mechanics.
  • Tight, ankle-driven kicking with minimal knee flexion creates propulsion without excess drag. The reason for this is that small-amplitude kicks generate thrust while avoiding splash and turbulence. This coordination with arm strokes produces lift forces rather than just maintaining position.
  • Slightly cupped hand position during the catch phase maximises water displacement for propulsion. This occurs because the curved hand shape creates pressure differences between palm and back surfaces, resulting in lift forces. Therefore, swimmers achieve forward thrust more efficiently than with flat hands.
  • Compact limb positioning during gliding phases minimises form drag. By keeping arms and legs close to the centerline, swimmers reduce frontal area and prevent water from catching on extended limbs, which leads to smoother forward movement.
Show Worked Solution

Sample Answer

  • Swimmers maintain head-spine alignment with horizontal body position to reduce form drag. This works because streamlined positioning allows water to flow smoothly around body contours, which prevents turbulence formation. As a result, resistance decreases by up to 40% compared to poor alignment.
  • Core muscle engagement keeps hips elevated at the water surface. This technique prevents legs from sinking below the body line, thereby reducing frontal surface area exposed to water. Consequently, form drag decreases significantly while buoyancy enables more efficient stroke mechanics.
  • Tight, ankle-driven kicking with minimal knee flexion creates propulsion without excess drag. The reason for this is that small-amplitude kicks generate thrust while avoiding splash and turbulence. This coordination with arm strokes produces lift forces rather than just maintaining position.
  • Slightly cupped hand position during the catch phase maximises water displacement for propulsion. This occurs because the curved hand shape creates pressure differences between palm and back surfaces, resulting in lift forces. Therefore, swimmers achieve forward thrust more efficiently than with flat hands.
  • Compact limb positioning during gliding phases minimises form drag. By keeping arms and legs close to the centerline, swimmers reduce frontal area and prevent water from catching on extended limbs, which leads to smoother forward movement.

Filed Under: Fluid Mechanics and Force Tagged With: Band 3, Band 4, smc-5879-20-Fluid resistance

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