Question

A body falls from rest. In the last second of its fall it covers half of the total distance. If g is 9.8 $m/s^2,$ then the total time of its falls is (in second) ?

• A. $2$
• B. $2+\sqrt{2}$
• C. $4-\sqrt{2}$
• D. $3$

Answer 1

Answer: (B)

$2+\sqrt{2}$

$h=\frac{1}{2}g{t}^2$
$\frac{h}{2}=\frac{1}{2}g(t-1{)}^2$
$t=2\pm \sqrt{2}s$
$t=2+\sqrt{2}s$