Question

A second's pendulum is mounted in a rocket. Its period of oscillation will decrease when the rocket is:

• A. moving up with uniform velocity
• B. moving up with uniform acceleration
• C. moving down with uniform acceleration
• D. moving around the earth in a geostationary orbit

Answer 1

The correct option is B moving up with uniform acceleration

Correct answer= B

As the rocket accelerates upwards, pseudo force acts in the opposite direction of propagation.

=> Pseudo force acts in downward direction and gets added up to gravitational force.

=> Effective gravity= gravitational force+ pseudo force

>Gravitational force

=> g' > g where g' = effective gravity

Since time period of oscillation of pendulum= √(L/g)

where L= length of the pendulum

g= gravitational force acting on the pendulum

=> In this situation,

time period of oscillation of pendulum=√(L/g')

Since g' > g

=> √(L/g') < √(L/g)

=> Time period of oscillation decreases