Answer:
The answer is 3.33m
Explanation:
The acceleration "a" is constant.
Acceleration is the variation of velocity over time,
.
solving the last equation
,
where
because the airplane starts from rest.
Once again, velocity is the variation of distance over time.

then

where
if we consider the end of the runway as the initial point (this step is for simplicity but you can let it expressed, it's going to cancel anyway).
If
at
, then

and the final expression for the distance is
.
If t = 2s, x = 4.44 m. Which means thad the additional distance is

Answer:
Explanation:
check attachment below for explicit explanation and answer.
V=v0+at=38m/s;
v^2=v0^2+2ad=>d=(v^2-v0^2)/2a=544/4=68m
It all depends on the SIZE of the balloon.
If the balloon is made of really tough rubber, and it holds the helium in the same volume as the solid iron block, then the buoyant force of the atmosphere is the same for both objects.
But if the balloon is just some flimsy stuff, and it lets the helium expand to a much bigger volume than the iron block, then the buoyant force on the balloon is greater than the buoyant force on the solid iron block.
In fact, it DOESN'T MATTER what's in the balloon and what's in the block. It doesn't matter whether either one of them is solid, liquid, or gas, and it doesn't matter whether they have the same or different mass.
Whichever one has greater VOLUME has a greater buoyant force of atmosphere acting on it.