Question:
A box is pushed through $4.0 \mathrm{~m}$ across a floor offering $100 \mathrm{~N}$ resistance. How much work is done by the resisting force?
Solution:
Resisting force
$\mathrm{F}_{\mathrm{R}}=\mathrm{F} \cdot \mathrm{d}$
$\mathrm{F}_{\mathrm{R}}=\mathrm{F} d \cos \theta=100 \times 4$
$\mathrm{~F}_{\mathrm{R}}=400 \mathrm{~J}$