WORK, POWER, ENERGY Flashcards
What is Work
VECTOR.
Change of position
Transfer energy to a system to move it
What is Power
SCALAR (because takes into account time)
Rate at which work is performed
What is Energy
SCALAR
Ability to do work
Because system is in motion
Why is more fatiguing to run on sand?
RUNNING ON SAND: sand absorbs energy which decreases velocity
RUNNING ON TRACK: rubber absorbs less energy which helps you maintain velocity
Positive Work VS Negative Work
POSITIVE WORK: movement occurs in same direction as force (CONCENTRIC)
NEGATIVE WORK: movement occurs in opposite direction of force pull (ECCENTRIC)
Give Example of Positive and Negative Work
EX POSITIVE WORK: lifting barbell
EX NEGATIVE WORK: lowering barbell (because bicep is generating force up but you are bringing object down)
Can you have work without movement?
NO MOVEMENT= NO WORK (thats why its called mechanical work)
What is Isometric Contraction?
ISOMETRIC: generating force with muscle but not moving.
What is Internal Work?
Moving the body…(raising arms above shoulder)
What is External Work?
Moving another system…(moving a shopping cart)
Power Equation
remember that
work= force*displcament
velocity= displacement/time
POWER: time-rate of doing things
Power (p) = Work/time
Power = force x displacement/time
Power = force x velocity
Units: Watts (J/s)
What is Ergometry?
ERGOMETRY: science that measures work and power
Energy equation
ENERGY: ability to do work
KE (kinetic energy) = ½mv^2
Units: Joules (J)
PE = magh (massgravityheight)
Units: Joules (J)
What is Kinetic Energy?
KE: ability to do work while moving
- the faster the ball is thrown the more work (force*displacment) you can do
- the heavier the ball used the more work you can do
What is Potential Energy?
PE: ability to create movement is dependent on POSITION of object
- the higher the hammer is held from nail the more work it can generate
- the heavier the hammer used the more work is can generate
