The new timeperiod is 1.41 times the old time period.
Now, consider a mass, m with time period "t" is oscillating.
Then,
The time period of a the oscillation of the ball is given as 2π[tex] \sqrt{ \frac{m}{k} } [/tex]
Now, if we need to find the time period,'t' when mass is doubled i.e 2m[tex]
\frac{t}{t'} [/tex]'= [tex] \frac{2 \pi \sqrt{ \frac{m}{k} } }{2 \pi \sqrt{ \frac{2m}{k} } } [/tex]
or, t' = t[tex] \sqrt{2} [/tex] = 1.41 t