A boy is swinging on a swing in sitting position. Its period if boy stands up will Increase, decrease, remain

A boy is swinging on a swing in sitting position. Its period if boy stands up will
Increase, decrease, remain same, may inc or dec

When the boy stands up, he is effectively moving his mass higher, thus shortening the length of the pendulum. The period of a pendulum is proportional to the square root of the length.
The period of a pendulum = 2pi sqrt(L/g) where L = length of pendulum.
Shortening this length decreases the period.

think of it this way: there is a center of mass while he is sitting.when he stands up,the center of mass will also move upward.
when we are sitting on the floor,our center of mass will be close to the floor,but when we stand up,our center of mass then will be somewhere near our belly or something.
so as period of a swing is proportional to the square root of the length of its swinging point to the center of mass,then standing will cause the length become short.
so the period will decrease.
so he will swing faster.

time period will decreased because person has made his centre of mass higher then before, and since time period is proportional to its length there for a small length will result in a short period .

Decrease. The period of a simple pendulum is proportional to its length.

Probably decrease because of a greater area for wind resistance