a body is thrown up in a lift with a velocity 'u' relative to lift and the time of flight is found to be 't'. the acceleration with which the lift is moving up is...

Dear Student,

Let the effective acceleration is g', then the equation for the time of flight is,

${T}_{f}=\frac{2u}{g\text{'}}⇒g\text{'}=\frac{2u}{t}⇒g+a=\frac{2u}{t}\phantom{\rule{0ex}{0ex}}⇒a=\frac{2u}{t}-g$