When the point of suspendion of pendulum is moved, its period of oscillation

Options

A. decreaes when it moves vertically upwards with an acceleration `a`
B. decreases when it moves vertcally downwards with acceleration greater than 2 g.
C. Increases when it moves horizontally with acceleration `a`
D. all of the above.

Answer

A, B

Explanation

When point of suspension of pendulum is moved upwards `g_(eff)=g+a`. `g_(eff)gtg` and as `Tprop(1)/(sqrt(g_(eff))`, hence T decreases, i.e., choice (a) is correct. When point of suspendion of pendulum is moved downwards and `agt2g`. Then `T` decreases i.e., choice (b) is also correct. In case of horizontal acceleration
`g_(eff)=sqrt(g^2+a^2)` i.e., `g_(eff)gtg`
i.e., Again `T` decreases.