2.09sec
Add them together then divide by three because there are three numbers
When object reached the terminal speed then its acceleration is zero
So as per Newton's II law we can say

now in that case we can say that net force is zero so here weight of the object is counter balanced by the drag force when it will reach at terminal speed
so we can write

so here we are given that





so terminal speed will be nearly 2 m/s
The correct answer is a I hope that helped enjoy the rest of your weekend
Bohr described the Planetary theory. the atom has a positive nucleus with electrons orbiting around them like planets.