Foundations Flashcards
Define Radian
A measure of the angle at the centre of a circle whereby the length of the arc is equal to the radius of the circle.
What is the value of one radian and how do you convert from degs to rads?
One radian = 57.3 degs Divide value (in degrees) by 57.3
What units do radians have?
None, a radian is a ration quantity between two lengths
Define the difference between angular distance and angular displacement?
Angular distance is a scalar quantity that reflects the angular length travelled per unit time, whereas displacement is a vector quantity which measures angular distance travelled, with respect to direction, per unit time.
Define angular velocity and how to calculate it.
Angular velocity is the change in angular displacement per unit time.
ω = Δangular displacement/Δtime
Define the difference between relative and absolute angles.
Relative angles are angles measured between two segments whereas absolute angles are defined relative to a line in space.
List the 4 biological locations in the 4 point model, used for digitising running.
- Greater trochanter
- Lateral femoral epicondyle
- Lateral malleolus
- 5th metatarsal-phalangeal joint.
What are the peak knee flexion velocities, as defined in the literature?
- 5rads/s (Milliron & Cavanaugh, 1990)
8. 9rads/s (Ferber, Davis, & Williams III, 2003)
What are the peak ankle dorsiflexion velocities, as defined in the literature?
- 5rads/s (Milliron & Cavanaugh, 1990)
8. 1rads/s ( Dixon, Collop, & Batt, 2000)
What is the cosine rule and what is its relevance in biomechanics?
a^2 = b^2 + c^2 -2bcCos(θ)
Used to calculate relative angles from marker data
During which phase of running is peak knee flexion and peak ankle dorsiflexion achieved?
During midstance - knee flexes and shank comes over the foot .
