Physics · Grades 7–12
Energy, work & power · Formula reference 1
Formula reference
Rule and assumptions
Work by an angled force
θ is the angle between the force and displacement, not an arbitrary drawing angle.
W = Fd cos θ
Change in kinetic energy
Square each speed before subtracting; a loss gives a negative change.
ΔEₖ = ½m(v² − u²)
Gravitational energy gain
Use the vertical height change and the specified constant field strength.
ΔEₚ = mgΔh
Useful output energy
Convert the efficiency percentage to a fraction; wasted energy remains part of the energy account.
Euseful = ηEin
Energy from constant power
Power is an energy-transfer rate; watts times seconds gives joules.
E = Pt
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Learning preview · independent educational and translation review required. Suggested grades are not official curriculum alignment.