Question

Suppose, the acceleration due to gravity at the earth's surface is $10{\text{ms}}^{-2}$ and at the surface of Mars is $4.0{\text{ms}}^{-2}$. A $60\text{kg}$ passenger goes from the earth to Mars in a spaceship moving with a constant velocity. Neglect all other objects in space. Which part of the figure best represents the weight (net gravitational force) of the passenger as a function of time?

• A. $A$
• B. $B$
• C. $C$
• D. $D$

Answer 1

The correct option is C $C$

There must be some point between Earth and Mars where the gravitational field of the earth is balanced by the gravitational field of Mars and hence the weight will become zero at that point.
This can be seen only in option (c).
Option (d) is eliminated because there can’t be $2$ points where the gravitational field will be zero and also because the weight can’t be negative.

Why this question? To make students familiar with the concept of gravitational field intensity and that it is a vector quantity. Key Concept: Between two masses, there will be a point where the gravitational field of one mass will be equal and opposite to the gravitational field of the other mass.