1
W = F · Δr = FΔr cos θ[W] = [F][L] = M(L/T)21 J = 1 kg·m2/s2
2
W = ∫rfri F(r) · drW = ∫xfxi F(x) dx =
3
W = ∫F dx = ∫mdvdtdx = ∫mv dvW = (1/2)mv2f − (1/2)mv2i = ΔKK = (1/2)mv2
4
Wg = mgd cos φvf = v2i ± 2gdWa + Wg = ΔK = 0 ⇒ Wa = mgd
5
Fs = −kdWs = ∫xfxi (−kx) dx = (1/2)kx2i − (1/2)kx2f[k] = N/m = kg/s2
6
Pavg = WΔtP = dWdt = F · v1 W = 1 J/s, 1 kWh = 3.6 × 106 J
7
ΔU = −W∮ F · dr = 0Wab,1 = −Wba,2 = Wab,2ΔU = −∫xfxi F(x) dx
8
U(y) = mgyU(x) = (1/2)kx2Emec = K + UΔK + ΔU = 0v = 2gh
9
mgh = (1/2)mv2 ⇒ v = 2ghv(y) = 2g(h0 − y)
10
W = F(x)Δx = −ΔU(x)F(x) = −dU(x)dxU = (1/2)kx2 → F = −kxU = mgy → F = −mg
11
(F − fk)d = (1/2)mv2 − (1/2)mv20W = Fd = ΔEmec + ΔEthΔEth = fkdW = ΔE = ΔEmec + ΔEth + ΔEintP = dEdt