Question

Define aceleration and give its si unit. When is accleration of
a body negative? Give two examples of situations is when
accleration of the body is negative​

Answer 1

Acceleration is the rate of change of velocity per unit time

Acceleration = v2 - v1 / time

Negative acceleration or deceleration is in the opposite direction of velocity

Example 1 : Brakes are applied on a moving vehicle

2 : A moving vehicle hits another one speeding towards it

Answer 2

Answer:

1. The rate of change of velocity is called acceleration.
2. It's SI unit is m/s square
3. When the speed of the body gets slow then it's acceleration is negative.

Situations

1. When a driver applies brakes on his vehicle.
2. When a plane is landing .

In both this situations speed is slowing down.