Chapter 33, Problem 12RQ

What causes a star to contract inwards?

To determine

The cause of contraction of star inwards.

Answer to Problem 12RQ

The force of gravity causes the contraction of stars inwards.

Explanation of Solution

There are two forces that act inside a star, that is the force due to gravity and the thermal pressure of nuclear explosion from which star is made. When these forces are balanced in the star, the star is in the stable stage.

The force due to gravity is responsible for the contraction of the star in inwards direction. There are fusion reactions occurs in the star, where hydrogen fuses into helium in the core.

As the fusion continues, carbon will be accumulating in the star’s core which is known as “ash”. The fusion then slowed down and will not be happening. The gravity predominates and the star contracts which boosts the temperature.

Conclusion:

Thus, the force of gravity causes the contraction of stars inwards.