work, power and energy Flashcards
work
when a force acts on a body, work done by the force is equal to magnitude x distance the body moves W = Fd (N)(m)
joule
N.m
positive work
negative
force in the same direction, body moves
opposite
concentric
muscular work
positive work
W = tensile force x distance the muscles stretches
power
rate at which at work is performed
P(ower developed) = W/t
watts
N.m/s
1 horsepower = 746 watts
energy
capacity to do work
mechanical
theres 3 types
kinetic
potential
strain
kinetic
energy bc of its motion
KE = 1/2 x mass x (velocity)squared
is used to deform an object to create strain energy + heat
potential energy
position in relation to earths surface
stored energy
gravitational energy
PE = weight x height above surface
strain energy
capaicty to do work while if reforms after being deformed
elastic potential energy
stored energy
SE = 1/2 x k(a spring constant) x x(distance over which the material is deformed)
law of conservation of mechanical energy
is constant when gravity is the only external force
PE + KE + SE = C
work
= change in KE + change in PE + change TE