00:01
All right, so what we have is a hot air balloon of diameter 12 meters.
00:04
We know that the mass of each person on board the balloon is 85 kilograms each.
00:09
The density of air is given to us as 1 .16 kilograms per cubic meter.
00:13
We know the density of helium, which is being able, which is being used to fill up this hot air balloon, has a density that is 1 -7th, the density of air.
00:21
We're asked to vary the number of passengers from basically 1 to 10, and we're asked to find the net acceleration just when the balloon is released.
00:30
So the first thing we're going to do is go ahead and solve for the volume of a balloon.
00:35
We're going to assume that the balloon is a sphere.
00:37
Therefore, the volume of the balloon will be equal to four -thirds pi -r cubed.
00:43
This gives us a volume equal to 904 .8 cubic meters.
00:51
Next, what we can do is we can use the equation for the force of buoyancy and use the density of air in this volume to solve for the buoyancy force.
00:58
So we can say that fb, which is our buoyancy force, is equal to row of air times gravity times bb.
01:09
And this gives a total buoyancy force of 10 ,296 newons.
01:14
Next, what we need to do is calculate our total mass.
01:17
So what we can do is solve for first the mass of helium that's inside our balloon and say that mhe is equal to row h .e times the volume of the balloon.
01:28
Which gives us a total mass of helium equal to 149 .9 kilograms...