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23 Cards in this Set
- Front
- Back
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Force
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A force is a push or a pull.
A force is something that has the ability to accelerate an object. |
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Internal Forces
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forces that act within the object or system whose motion is being investigated. Alone, these forces cannot change the motion of the body center of mass.
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External Forces
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forces that act on an object as a result of its interaction with the environment surrounding it. These forces can change the motion of the body center of mass. Many sport biomechanists are concerned most with external forces.
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Non-Contact Forces
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forces that do not require contact between two objects; the non-contact force of primary concern is gravity, which causes an acceleration of -9.81 m/s/s
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Static Equilibrium
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When an object is at rest and the forces acting on the object are in equilibrium, they result in a net force of zero.
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Kinematics
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is the branch of dynamics concerned with the description of motion.
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Rectilinear Translation
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Occurs when all points on a body or object move in a straight line so the direction of motion does not change, the orientation of the object does not change, and all points on the object move the same distance.
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Curvilinear Translation
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Occurs when all points on a body or object move so that the orientation of the object does not change and all points on the object move the same distance. The lines created by the points are curved rather than straight.
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Angular Motion
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Occurs when all points on a body or object move in circles (or parts of circles) about the same fixed central line or axis. The object continually changes direction and orientation.
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What is the difference between distance and displacement?
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Distance is the length of the path traveled when changing position, and displacement is length and direction of the vector from the starting and ending position vector.
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Speed, compared to velocity
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Average Speed = Distance/Δ Time
Average Velocity = Displacement/Δ Time |
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one three factors can one manipulate to influence the horizontal displacement of a projectile
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Relative height of release
Speed of Release Angle of Release |
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What is the optimal release angle
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When height release is zero angle is 45
As height of release ↑, optimal angle ↓ |
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Theoretically optimal angle is about 42°
•Top long jumper use angles of 17-23° •Way off! Why the major discrepancy? |
Sacrifice optimal angle for maximal speed
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Projectile Motion
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any motion in which gravity is the only acting external force
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What two factors does post-impact velocity primarily depend upon?
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Quality or Elasticity of impact
Pre impact velocity |
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What are the components of power production?
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strength(force producing ability) and speed of muscle contraction
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Work
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quantity describing the extent to which a force can move an object
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Energy
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ability to perform work
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Power
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rate of change of work
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Pronation (subtalar joint)
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a combination of dorsiflexion, eversion, and abduction
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Supination (subtalar joint)
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a combination of plantarflexion, inversion, and adduction
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What is not a mechanical factor in determining the stability of a person?
a. The height of the whole-body center of mass b. The weight of the person c. The nature of the base of support d. The fiber type of the lower extremity musculature |
d. The fiber type of the lower extremity musculature
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