abstract
action
activity
balance
black
bright
bulb
colliding
concept
conservation
conserve
cradle
economical
effect
efficiency
electric
evolution
force
glass
glowing
gravity
green
hanging
idea
illuminated
illumination
impact
incandescent
innovation
invention
lamp
led
mass
motion
pendulum
perpetual
physics
power
progress
recycle
save
science
shine
solution
swinging
technology
timer
wire