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Chapter 6: The biomechanics of human movement 

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Summary quiz

Using the words below, complete the following statements by filling in the blanks.

absorb

angular

biomechanical

buoyant

centre

density

displaced

distance

distribution

drag

fluid

force

gravity

greater

injury

less

lift

line

linear

motion

movement

opposes

profile

rapidly

science

short

spinning

support

surface

third

time

velocity

wet

wide

1. Biomechanics is a science concerned with forces and the effect of these forces on

the human body. A knowledge of biomechanics helps us choose appropriate

equipment, improve technique and reduce the risk of injury.

2. Motion is the movement of a body from one position to another.3. There are three types of motion — linear, angular  and general.

4. Velocity is equal to displacement divided by time. It is useful when calculating how

quickly people or objects travel when their path is irregular (cross-country runner) or

curved (javelin thrower).

5. Speed is equal to the distance covered divided by the time taken.

6.  Acceleration is the rate at which changes in a given amount of time. It is very

important in short distance events.

7. Momentum is the quantity of force a body possesses. It is most apparent in collisionsituations. When this happens, momentum continues in the direction of the body with

the mass (as long as other factors are equal).

8. Momentum can be (in a straight line) or angular (moving around a point).

 Angular momentum can be seen in most activities, particularly when we use

equipment such as sticks, bats and clubs.

9. The centre of gravity of an object is the point about which all the weight is evenly

distributed. In humans it is located approximately at waist height and in the middle

between the front and back of the trunk.

10. Knowledge of the location of the centre  of gravity has important implications for

sporting events such as high jump.

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Chapter 6: The biomechanics of human movement

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11. The line of gravity is an imaginary vertical line passing through the centre of gravity

and extending to the ground.

12. The base of support refers to an imaginary line that surrounds the outside of the body

when it is in contact with a surface. We improve balance by using a base of

support. It becomes increasingly difficult to balance as we narrow the base of

support.

13. Fluid mechanics is a branch of mechanics concerned with properties of gases and

liquids.

14. Our body floats when the forces created by its weight are matched equally or better

by the drag force of the water.

15. Body desnity, or its mass per unit volume, impacts on the ability to float. A body or

object floats if its density is l…less…. than that of the fluid.

16. The weight and distriubtion  of organs and tissues throughout the body influences

flotation and the way the body floats (or sinks).

17. The centre of buoyancy is the centre of gravity of a volume of water displaced by an

object when it is immersed in that water.

18. Drag is the force that oposes  the forward motion of a body or object, reducing its

speed or velocity.

19. Lift is the component of a force that acts at right angles to the drag.

20. The amount of force  is influenced by fluid density, object shape (bulky or

streamlined), surface smoothness and size of the frontal area.

21. drag or skin friction refers to a thin film of the fluid medium sticking to the

surface area of the body or object through which it is moving.

22. drag (also called form or pressure drag) refers to drag created by the shape

and size of a body or object.

23. The Magnus effect explains why spinning objects such as cricket and tennis balls

deviate in the air from a normal flight path.

24.  A force is the push or pull acting on a body. The body applies force in movements

such as running and jumping. These applied forces are met equally by reaction

forces. The concept of applied and reaction forces is explained by Newton’s 3rd law.

25. Power is the application of force applied rapidly. Power is important to most activities,

usually of short duration, such as jumping, starting in athletics and throwing.

26. In both landing and ball-catching situations, forces can cause pain and sometimes

injury. A knowledge of principles helps us learn to these forces

effectively.

27. The mass of commonly used sporting objects, such as soccer balls, can vary within a

game if they become . The current mass of the object determines the amount of

force that needs to be applied to gain the desired result.