The final velocity of an object is less when the acceleration is negative. This means that the object is slowing down. The acceleration of an object is the rate at which its velocity changes. When the acceleration is positive, the object is speeding up. When the acceleration is negative, the object is slowing down.

The equation for final velocity is:

```

v = u + at

```

where:

* v is the final velocity

* u is the initial velocity

* a is the acceleration

* t is the time

If the acceleration is negative, then the final velocity will be less than the initial velocity. This is because the negative acceleration will cause the object to slow down.

For example, if an object is thrown upwards with an initial velocity of 10 m/s, the acceleration due to gravity will be -9.8 m/s^2. This means that the object will slow down as it rises. The final velocity of the object will be 0 m/s when it reaches its highest point.