When you balance on a skateboard there are three forces at work.

I wrote>
When you balance, on a skateboard there are three forces at work.

The comma doesn't belong after balance. Where is the correct place to place a comma?

after skateboard

Right.

To explain the three forces at work when balancing on a skateboard, we need to consider the principles of Newton's laws of motion.

1. First Law - Inertia: This law states that an object at rest will stay at rest, and an object in motion will stay in motion with the same speed and direction unless acted upon by an external force. When you balance on a skateboard, your body's natural tendency is to maintain its current state of motion, whether it is at rest or in motion. This means that if you are standing still on the skateboard, you will resist any changes to your position or posture.

2. Second Law - Acceleration: For any object to accelerate or change its motion, a force needs to be applied. When you move your body, specifically your center of mass, on the skateboard, you create a force that causes an acceleration. This force is provided by the muscular efforts of your body. By shifting your weight or applying pressure with your legs or feet, you can produce the necessary forces to maintain balance on the skateboard.

3. Third Law - Reaction: This law states that for every action, there is an equal and opposite reaction. When you push or exert a force on the skateboard, the skateboard exerts an equal and opposite force on your body, allowing you to maintain balance. It is this interaction between the forces you apply and the reaction forces from the skateboard that allows you to adjust your position and counteract any external disturbances, such as changes in terrain or sudden movements.

In summary, the three forces at work when balancing on a skateboard are:

1. Inertia, which resists changes to your position or posture.
2. Acceleration, generated by your body's muscular efforts to maintain balance.
3. Reaction, the interaction between the forces you apply and the reaction forces from the skateboard to adjust and counteract external disturbances.