CH 7: Kinetic and Potential Energy Flashcards
what is energy
energy is a quantity that tells us about an objs ability to do work, or tells us about the transfer of heat
its conserved
when does a force do work
when the obj has displacement, and when the force has a component is the direction of movement (parallel)
If 𝜃 = 90 then no work is done. If 𝜃 > 90 then
work is negative.
what is conservation of energy
Wnet = difference of KE = KE,f - KE,i
what is kinetic energy
moving obj,
KE = 1/2mv^2
what is potential energy
gravitational in this course
PE = mgy
what is the relationship between work and energy
work is a form of energy
Wnet = difference of KE = KE,f - KE,i
what units is work/energy
Joules (F*m)
whats a non conservative force
for some forces, some work depends on the entire path that an obj is moved (friction, pushes, pulls)
𝑊1 ≠ 𝑊2 ≠ 𝑊3
whats a conservative force
some forces, the work done only depends on the beginning and end points of the path (gravity, springs, electrostatic)
W1 = W2 = W3
how to know when to use Wnc or Wc
a big hint is if theres friction stated
friction removes energy from the system, which makes it non conservative
what is power
the rate of energy use/output
P = difference of energy/difference of time
what is the unit for power
J/s = watt= W
