Chapter 7, Problem 9TE

A friend says that astronauts in orbit are weightless because they are beyond the pull of Earth’s gravity. Correct your friend’s ignorance.

To determine

Correction in the friend's ignorance about the weightlessness of the Astronaut in orbit.

Answer to Problem 9TE

The friend’s statement on the gravitational pull is incorrect because the weightlessness of the Astronaut is due to net-zero force and zero reaction, not due to the absence of the pull of the gravity.

Explanation of Solution

Any object that moves around another object in circular motion requires the necessary force to continue its motion. The force that continues the circular motion of the object is called the centripetal force.

The Earth pulls every object towards its surface due to the gravitational force of the Earth on the object. The gravitational pull of the Earth on the Astronaut provides the necessary centripetal force for the motion of the Astronaut in orbit. The gravitational force remains equal to the centripetal force of the Astronaut, so the net force on the Astronaut becomes zero.

As the net force on the Astronaut remains zero in orbit, so the reaction of the weight of the Astronaut also becomes zero and Astronaut feels weightless in orbit.

Conclusion:

Therefore, the friend’s statement on the gravitational pull is incorrect because the weightlessness of the Astronaut is due to net-zero force and zero reaction, not due to the absence of the pull of the gravity.