4 - 16 Work and power
● Energy transferred = ability to do work = work done
○ ***W ( work done[ J ])=F (force [ N ])∗d( distance moved [m])
Gravitational potential energy (GPE)
●
GPE [ J ]=m(mass , of object [kg])∗g(gravitational field strength[N /kg])∗h (height [m])
○ ∵ Earth’s g known as 10 N/kg, 1 kg = 10 N (m∗g )
○ ∴ ***GPE [J ]=w( weight [N ])∗h(height [m])
●
Kinetic energy (KE)
1 2
● KE [J ]= ∗m(mass [ kg])∗v (speed , squared[m/s , squared ])
2
—————————————————————————————————————————
● ***Work done (lifting object) = gain in GPE = loss in KE
Power
● Rate of transfer of energy/rate of doing work
W (work done [J ])
● *** P( power [W ])=
t(time taken[s ])
○ ∴ J = Ws
1
● Energy transferred = ability to do work = work done
○ ***W ( work done[ J ])=F (force [ N ])∗d( distance moved [m])
Gravitational potential energy (GPE)
●
GPE [ J ]=m(mass , of object [kg])∗g(gravitational field strength[N /kg])∗h (height [m])
○ ∵ Earth’s g known as 10 N/kg, 1 kg = 10 N (m∗g )
○ ∴ ***GPE [J ]=w( weight [N ])∗h(height [m])
●
Kinetic energy (KE)
1 2
● KE [J ]= ∗m(mass [ kg])∗v (speed , squared[m/s , squared ])
2
—————————————————————————————————————————
● ***Work done (lifting object) = gain in GPE = loss in KE
Power
● Rate of transfer of energy/rate of doing work
W (work done [J ])
● *** P( power [W ])=
t(time taken[s ])
○ ∴ J = Ws
1
