### The Special Theory of Relativity

goals
On passing through a wooden sheet a bullet loses $1/20$ of initial velocity. The minimum number of sheets required to completely stop the bullet will be:
Who proposed general theory of relativity?
What is the famous relation in physics which  relates 'moving mass' m to the ' rest mass ' $m_{0}$ of particle in terms of its speed v and the speed of light c. (this relation first arose as a consequence of special relativity)
What is the reason for constant speed of light for all the observers ?
A block of mass $4kg$ and dimensions $10cm\times 20cm\times 30cm$ rests on the floor. If $g=10m$ $s^{-1}$, then the maximum pressure the block can exert on the floor is