Question

An astronaut is in a stable orbit around the earth when he weighs a body of mass $5kg$. What is the reading of spring balance?

• A. Spring will not be extended
• B. Spring will be extended according to Hooke’s law
• C. Less than $5kg-wt$
• D. More than $5kg-wt$

Answer 1

The correct option is A

Spring will not be extended

Step 1. Given Data,

Mass $m=5kg$

Step 2. Reading of spring balance,

We know that, Hooke's Law,

$F=-kx$ (where $k$ is called the spring constant, $F$ is Force and $x$ is length).

When a spring is stretched or compressed, then its length changes by an amount $x$ from its equilibrium length, and then it exerts a force $F=-kx$ in a direction toward its equilibrium position.

Since there is no gravity $g$ in space.

Thus,

$$\begin{gathered} F=mg \\ \Rightarrow F=5\times 0 \\ \Rightarrow F=0 \end{gathered}$$

Hence, spring will not be extended.

Hence option (A) is correct.