Module 2 Flashcards
Define energy and forms of energy (2)
the capacity to do work
kinetic - energy a system has because of its motion
potential - energy that is stored in a system because of its position
define kinetic energy
kinetic - energy a system has because of its motion
potential energy
potential - energy that is stored in a system because of its position
define work
process of energy being transferred between physical systems.
or in other words, force applied over a distance.
define gravitational potential energy
energy a system stores due to its vertical position or height in a gravitational field.
energy consumption/dissipation
the energy that is used to produce work and as a result is dissipated.
define the exchange of energy. Describe a model that demonstrates this.
what is the equation?
exchange of energy from one form to another (kinetic to potential or vice versa)
example: frictionless rollercoaster. At the peak, the roller coaster has 100% potential energy and 0%
(for the vertical component, the horizontal component still has kinetic energy from the initial push that caused the coaster to move in the first place).
Equation: Em = Ek + Ep
Energy (mechanical) = Energy (kinetic) …
why does it take energy to walk unlike the hypothetical rollercoaster?
Because there is some friction in our joints and interaction with the environment around us
how do you measure energy expenditure
may involve measures of CO2, or O2 consumption, temperature change, or some combination of those things
What are some ways humans minimize energy expenditure in locomotion?
- utilize exchange of kinetic energy to gravitational potential energy by falling forwards to step (muscles take care of the rest).
- deactivating certain muscles during the swing phase
why is friction important for movement
which of newtons laws does this use
because it allows us to use reaction forces to create movement.
third law - for every action, there is an equal and opposite reaction
when stepping on the ground, the vertical reaction force is always ____. The horizontal reaction force does what?
what does the graph of vertical and horizontal reaction forces look like?
Positive (pushing you up)
Horizontal force pushes back at you initially, then propels you forwards (push forwards).
vertical forces looks like “M” and is always positive. Horizontal reaction force goes from 0 to negative then straight line to positive, then back to 0.
What are the phases in the gait cycle ()
- Right heel strike
- Left toe off
- Right mid stance
- Left heel strike
- Right toe off
- Left mid stance
step length
distance between left and right foot plant from heel
step width
the width between feet when stepping
stride length
one complete cycle, from one foot step back to same foot step.
foot angle
the angle of the foot (points a little out usually)
what is the relationship with hip extension and flexion when graphed compared to knee
the relationship correlates, hip is extended when knee is extended, sme for flexed
is there a way to define optimal gait kinematics mathematically?
is ir realistic
how can we assess gait
yes,
not so realistic (probably nobody follows it).
observe and compare joint angles and other gait parameters
What muscles control what part of the gait cycle?
- heel strike: gluteus max + med, vasti muscles (quads)
- mid stance: glutes (max and med), vasti muscles, soleus, gastrocts
- toe off: Gastrocts, soleus,
What does gait look like with a stiff knee gait (if graphed)
first part of graph is flat, second part has some increased angle on swing phase.
