Answer:
Dummies deceleration is 11m/s²
Step-by-step explanation:
According to Newton's second law, the relationship between the force applied to an object, its mass, and the acceleration (or deceleration) caused, is given by:

Solving for acceleration:

If we plug in the vales (taking into account the negative sign of the force, as its directed backwards):


Deceleration is simply the magnitude of negative acceleration. Therefore, dummies deceleration is 11m/s²