Final answer:
The acceleration of a 72 kg object when a force of 399 newtons is applied is 5.54 m/s², which is option a.
Step-by-step explanation:
The question relates to calculating the acceleration of an object using Newton's second law of motion, which states that the force applied to an object is equal to the mass of the object multiplied by its acceleration (F = ma). To find the acceleration, you need to rearrange the equation to solve for acceleration (a = F/m).
In this case, the force (F) applied is 399 newtons and the mass (m) of the object is 72 kilograms. Therefore, the acceleration (a) can be calculated as follows:
a = F/m
a = 399 N / 72 kg
a = 5.54 m/s²
So, the acceleration of the object is 5.54 meters per second squared, which corresponds to option a.