Question:
A girl is carrying a school bag of $3 \mathrm{~kg}$ mass on her back and moves $200 \mathrm{~m}$ on a levelled road. The work done against the gravitational force will be $\left(g=10 \mathrm{~m} \mathrm{~s}^{-2}\right)$
(a) $6 \times 10^{3} \mathrm{~J}$
(b) $6 \mathrm{~J}$
(c) $0.6 \mathrm{~J}$
(d) zero.
Solution:
(a). Freely falling bodies moves with constant acceleration.