What is the difference between mass and weight?

Explain why we feel that our weight is decreased in a lift descending with uniform acceleration.

What are spring tides? Why are they formed? Explain.

A body dropped from a height of $5 \mathrm{m}$, reaches the ground in $1 \mathrm{s}$. If it takes $2 \mathrm{s}$ to reach the ground, find the height from which it is dropped.

A body is dropped from a certain height and, it reaches the ground in $2 \mathrm{s}$. Another body which has twice the mass as that of the first body, when dropped reaches the ground in $4 \mathrm{s}$. Find the ratio of velocities acquired by them when they reach the ground.