There are two springs $A$ and $B$. Both have spring constant of $100 {\mathrm{Nm}}^{-1}. A$ is compressed by $5 \mathrm{cm}. B$ is stretched by $5 \mathrm{cm}$. What is the difference in $PE$ stored in the two springs?

(a) Two bodies of masses $m_1$ and $m_2\left(m_2>m_1\right)$ are dropped from the same height. Compare their momentum just before hitting the ground.

(b) Two bodies of masses $m_1$ and $m_2\left(m_2>m_1\right)$ have same $KE$. Compare their momentum.