question_answer

 A body dropped from an aeroplane moving upwards with a uniform velocity of 19.6 m/s reaches the ground after 12 seconds. What is the height of the aeroplane when the body is dropped from it?

Answer:

\[-h=ut-\frac{1}{2}g{{t}^{2}}\] \[-h=19.6\times 12-\frac{1}{2}\times 9.8\times 12\times 12\] \[=19.6\times 12(1-3)=-24\times 19.6=470.4\,\,m.\]