Explanation:
We have,
Speed of plane a is 900 km/h
Plane b is moving at a rate of 
It is required to find which plane is faster. To find which plane is faster, we need to compare their speeds.
Speed of a plane a is 900 km/h and that of plane b is 50 km/h. So, we can say that plane a is moving faster.
Answer:
they are both clocks i think please be right
Answer: 
Explanation:
We know the total diameter of the cell (assumed spherical) is:

Then its total radius 
On the other hand, we know the thickness of the cell wall is
and its density is the same as water (
).
Since density is the relation between the mass
and the volume
:

The mass is:
(1)
Now if we are talking about this cell as a thin spherical shell, its volume will be:
(2)
Where 
Then:
(3)
(4)
Substituting (4) in (1):
(5)
(6)
Knowing
and
: