Maharashtra State Board · Class 10 · Physics · Chapter 2

Work, Energy and Power — Formula Sheet

Board Formulas

8 formulas

1.Work Done by a Constant Force★
$W = F s cos θ$
$W$ : Work done (J) · $F$ : Applied force (N) · $s$ : Displacement (m) · $θ$ : Angle between force and displacement
θ is angle between force and displacement. When θ = 90°, W = 0.
2.Kinetic Energy★
$K E = \frac{1}{2} m v^{2}$
Energy due to motion. Scalar. Always positive.
3.Gravitational Potential Energy
$P E = m g h$
Energy due to position above a reference. Valid near Earth's surface where g is constant.
4.Work–Energy Theorem★
$W_{n e t} = Δ K E = \frac{1}{2} m v^{2} - \frac{1}{2} m u^{2}$
Net work done on a body equals its change in kinetic energy.
5.Power (Average)
$P = \frac{W}{t}$
Rate of doing work. Unit: watt (W) = 1 J/s.
6.Power (Instantaneous)
$P = F v$
Useful when force and velocity are constant along the same line.
7.Conservation of Mechanical Energy
$K E + P E = constant$
In absence of friction, total mechanical energy is conserved.
8.Commercial Unit of Energy
$1 kWh = 3.6 \times 1 0^{6} J$
Electricity bills use kWh (1 unit). Convert to joules for SI calculations.