topic 8 - forces and energy Flashcards
what happens to energy when a system changes
energy is transferred and some energy is dissipated
how can a system be changed
by forces doing work, electrical equipment doing work or. heating
what is work done
energy transferred when a force moves an object through a distance
work done =
force x distance
change in gravitational potential energy =
mass x GFS x change in vertical height
kinetic energy =
0.5 x mass x velocity^2
how to reduce friction between objects’ surfaces when they move
lubrication
efficiency =
useful energy transferred / total energy supplied
what is power
rate of energy transfer
power =
work done / time
energy transferred is equal to
work done
one watt is equal to
one joule per second
what is contact force
when two object have to be touching for a force to act
what is a non contact force
if two objects do not need to be touching for the force to act
moment of a force =
force x distance normal to the direction of the force
