College Physics.
posted by Jay .
A pendulum has a period of 1.8 s.
a) Its mass is doubled. What is its period now?
b) Its length is doubled. What is its period now?
The original pendulum is taken to a planet where g = 16 m/s2.
c) What is its period on that planet?

You should be able to figure these out yourself using the formula for the Period:
P = 2 pi*sqrt(L/g)
Note that it does not depend upon the mass of the pendulum. 
really?? but how would i find L?

If you double L (the length), P increases by a factor sqrt2 = 1.414, no matter what L is.

(a) time period is independent of mass. so time period of pendulum remains same.
(b)
let initial time period be t1 when length is l and t2 be time period after double of length,i,then
t1=sqrt(l/g)....(1)
t2=sqrt(2l/g)
=root 2xsqrt(l/g)....(2)
from 1 and 2,
t2=root 2 times t1
where t1=1.8 s
(c)ti/t2=sqrt(g'/g)
where g=9.8m/s,ti=1.8s and g'=16m/s
solve n u will get answer