**Alcohol** negatively affects driving ability in several ways, leading to an increase in the vehicle's **stopping distance**. This is due to several factors:

- **Slower reaction:** Under the influence of alcohol, you need more time to react to situations on the road. This means it takes longer to start braking when you see an obstacle or danger.

- **Poor coordination:** Alcohol impairs the coordination of movements, which can affect the ability to brake effectively and quickly.

- **Altered perception:** Alcohol affects how you see the environment, including the ability to correctly judge distances. This can lead to errors in judging when to start braking.

- **Incorrect decisions:** With alcohol, there is a higher probability of making poor decisions or not knowing how to carry them out, which can include when and how to brake.

In summary, alcohol consumption while driving increases the stopping distance because it affects reaction, coordination, perception, and decision-making, making the process of stopping the vehicle slower and less precise.