Question

A a ball falling freely covers -9/25 in of total distance during last second of its fall. Total time of its fall will be.

Answer 1

DATA

Total distance= S

Tota time=t

Last second=t-1

distance covered during last second = 9/25 S

FORMULA

• S(t)=1/2gt²

• S (t-1) =1/2g(t-1)²

• 9/25 (1/2 gt²)=1/2 g(t-1)²

• 0.18 g t² =0.5g(t²-2t+1)

• 0.36t²=t²-2t+1

• 0.64 t²-2t+1=0

Solving quadratically

• a=0.64

• b=-2

• c=1

X=(-b±√(b^2-4ac))/2a

t= 5/2

or

t=5/8

ANSWER

{2.5s} or {0.6s}