Chapter 3 - biomechanics

what is a force?

a push or pull that can change motion

what is weight?

force due to gravity acting on the body

what is friction?

force that opposes motion between surfaces

what is inertia?

resistance to change in motion

what is newtons first law of motion?

an object will remain at rest or in motion unless acted upon by an external force

what is newtons second law?

force = mass x acceleration

what is newtons third law?

every action has an equal and opposite reaction

what is linear motion?

movement in a straight line, where all parts of the body move the same distance, same direction

what is angular motion?

rotation around an axis

what is general motion?

combination of linear and angular motion

speed formula

speed = distance/time

velocity formula

velocity = displacement/time (has direction)

what is acceleration?

the rate of change of velocity

what is momentum? and what is it’s formula?

how hard it is to stop and object in motion.

momentum = mass x velocity

what is impulse?

the change in an objects momentum.

impulse = force x time

impulse = change in momentum

what 3 factors affect projectile motion?

angle, speed and height of release

what is the optimal angle if release height = landing height

45 degrees

what is the optimal angle if release height > landing height

> 45 degrees

what is the optimal angle if release height < landing height

> 45 degrees

what is sequential summation of force?

start with large body parts to smaller body parts to maximise force and power

what is simultaneous summation of force?

body parts move at the same time to maximise accuracy

what is stability? and what can increase stability?

ability to maintain balance

things that can increase stability: increase base of support, lower center of mass, keep the line of gravity within the base of support

what is static equilibrium?

balance when the body is not moving

what is dynamic equilibirum?

balance while the body is moving

what is the centre of gravity?

the point in the body around which mass is evenly distributed

what is the line of gravity?

imaginary vertical line through the centre of mass

what is torque? and what is its formula?

turning force around an axis of rotation

torque = force x length of moment arm

what is moment of inertia?

resistance to rotation

what is angular velocity?

the speed of rotation around an axis

what is a third class lever? and what is the advantage of them?

when the force is between the axis and resistance

mechanical advantage < 1 (favours speed)

components of a level

axis (joint), force (muscle), resistance (load)