Chapter 11 Flashcards
(12 cards)
What are external forces?
Forces that originate outside the body, such as gravity and wind resistance
External forces can work to our advantage or disadvantage, like gravity during skydiving.
What are internal forces?
Forces that arise within the human body, generated by muscle contractions
Example includes a bicep curl, where the biceps contract to move the forearm.
Define statics.
The branch of mechanics that studies an object or body’s state of constant, unchanged motion.
Define dynamics.
A branch of mechanics that studies changes in the motion of objects or bodies due to forces.
What is Newton’s First Law of Motion?
A body in motion tends to stay in motion and a body at rest tends to stay at rest unless acted upon by an external force
Example: a gymnast holding a stationary pose on a balance beam.
What is Newton’s Second Law of Motion?
A force applied to an object causes an acceleration proportional to the force and inversely proportional to the object’s mass (F=ma)
Example: a basketball thrown into the air accelerates in the direction of the applied force.
What is Newton’s Third Law of Motion?
For every action, there is an equal and opposite reaction
Example: a basketball player jumping for a slam dunk pushes against the court floor.
What characterizes first class levers?
The fulcrum is located between the point of application of muscular force and the resistance
Example: the neck during flexion and extension.
What characterizes second class levers?
The resistance is positioned between the point of application of muscular force and the fulcrum
Example: the ankle joint with the gastrocnemius muscle.
What characterizes third class levers?
The point of application of muscular force is found between the fulcrum and the resistance
Example: a bicep curl.
Define linear motion.
When a body moves the same distance in the same direction in the same amount of time, characterized by straight line motion
Example: running straight ahead.
Define angular motion.
Features a rotation or turning about an axis, not acting through the center of an object
Example: a figure skater spinning.
