Biomech Theory Review (Midterm)

What is biology and mechanics?

• Study of living things

M

• Branch of science and physics that deals with the interaction between forces and objects

What is Biomechanics?

• The science of applying principles of mechanics to the study of living things where we only care about humans and the human interaction with forces + objects

Why do we learn biomech?

• Helps us fully understand how force affects the human body

  • Gravity and its effects on our mass

  • Forces and impacts causing injury

  • Stimulating overload that encourages / promotes bone and muscle growth

• How to accurately describe human movement and movement patterns

  • Optimize movement patterns to optimize performance

  • Identify faulty and usual movement patterns

What is accuracy and discrepancy?

• How close the measured value is to the actual value

• Discrepancies is the measurement error

  • the difference between measured vs actual

What is precision? What is uncertainty?

• How similar are repeated measurements

Uncertainty is the deviation from 1 measurement to another.

What are measures of central tendency?

• Help describe large sets of data by representing where the data centers around

  • Average, arithmetic mean (mean or avg)

    • Sum of the values / # of values you have

What are distributions?

How far apart or how spread apart the values are in the dataset.

• Variance

  • Average of the squares of of the difference from the mean data

  • Unit changes after calculation (becomes squared)

What is standard deviation?

• Square root of the variance

• e.g. 2/3 = 0.666 (square rooted = 0.816) which is 1SD of the mean

What are the general sig fig rules for calculations?

• The # of sig figs in the final answer must be no greater than the # of sigfigs in the least precise measured value

• Rule 1: For division / multiplication → the result should have the same # of sigfigs as the inputted # with the least # of sigfigs

• Rule 2: For addition / subtraction → the answer can containt no more decimal places than the least precise measurement

What are the units of the system internationale used for biomechanics?

Length → meters

Time → Seconds

Mass → KG

Force → Newtons (N)

What are the imperial unit conversions?

1 inch = 2/54

1 mile = 1600 m or 1.6km

1kg = 2.21 lbs

What are forces?

• may accelerate (change speed) or deform (change in objectivity

• Occur in pairs

• Measured in Newtons

What is the law of inertia?

• A body in constant motion will remain in constant motion unless affected by an unbalanced external force AND a body not in motion will remain not in motion unless affected by an unbalanced external force

What is the law of acceleration?

Force = mass x acceleration

Force required to move a mass is proportional to acceleration.

F=ma

What is the law of action and reaction?

• Every action has an equal and opposite reaction

What can be said about forces in terms of vectors and system of interests?

• Has both a magnitude / size and direction

• Can be represented graphically by arrows and other vector quantities (acceleration, velocity)

  • Mass, distance and speed (vector quantities)

There is also an internal system of interest

• Forces which act within the object (don’t affect the motion of the object system

And an external system of interest.

• act on an object due to to an interaction between objects or with a larger outside environment → will affect the motion of the object system (so long as they are balanced)

What are differences that can be seen in terms of direction?

• Twisting force

• Bending Force

• Tension (tensile force)

• Compressive force

• Shearing force

What is Kinematics?

• Mechanics is the branch of science that investigates motion and the forces that causes it.

• Kinematics is the study of motion without reference to the forces that cause motion

• Where linear kinematics is interpreted in straight lines while angular kinematics is motion in curved lines or on an axis

What is kinetics?

• The study of motion with reference to the forces that caused that motion

• Linear: study of forces in straight lines

• Angular: Study of forces in around or about an axis

How does mass differ from weight?

Mass is proportional to the amount of matter in an object which is reflected on object’s inertia.

• Weight is a force which acts on object’s mass due to gravity.

• Gravity is an attraction between masses, we only consider the gravity of massive objects on earth.

• Gravity acts on masses linearly in a down ward direction pulling the objects directly to its center.