Simple pendulum on International Space station

SIMPLE PENDULUM ON ISS

INTRODUCTION

The International Space Station [ISS] is a satellite orbiting earth at approximately 250 miles from the surface. Consider a pendulum aboard the ISS. A pendulum is a weight suspended from a pivot so that it can swing freely. It has a bob [mass] suspended from a frictionless pivot via a string. The central position of the bob i.e. when the pendulum is at rest is called its Mean position. When the bob is made to swing on the application of external force, it oscillates back and forth about this mean position. The maximum distance traversed by the bob from the mean position is known as amplitude. The amplitude is measured in radians which is a unit of angle. The time taken by the pendulum to complete one full oscillation is called the Time Period. For small amplitude less than 1 radian, the time period is independent of amplitude of the pendulum. We intend to determine the time period of such a pendulum on ISS. The ISS is always in a state of free fall hence all objects inside ISS will experience weightlessness.

A simple pendulum

ASSUMPTIONS

1. The string has no tension or compression

2. The pendulum is indestructible

3. Air resistance is negligible

CALCULATION

The time period of a simple pendulum is given by,

T = 2π*√ (l/g) (Eqn. 1)

Where,

T – Time period [s]

l – Length of the pendulum [m]

g – Acceleration due to gravity on ISS [m/s²]

g = 0 m/s² {due to free fall} (Eqn. 2)                 

Let the length of pendulum be

l = 1 m (Eqn. 3)

Now substitute equations (2), (3) in equation (1)

T = 2π*√ (1/0)

T = 2π*√ (∞)

T = 2π*∞

T = ∞ s (Eqn. 4)

This is the time period of a simple pendulum on ISS. This clearly indicates that Time period does not exist for the pendulum inside ISS. Even when a small force is applied to the bob, the bob will just move in one direction and never return to the mean position due to lack of gravity.

CONCLUSION

We thus concluded that the pendulum will not work aboard the ISS due to lack of gravity.